Yuuki Tenpouin

Yuuki Tenpouin (天宝院遊騎, Tenpouin Yuuki) is a Code:Breaker whose codename is Code: 03. He has the ability to manipulate sound.

Basic Information
Yuuki speaks using Kansai-ben. He sleeps in a mansion and is referred to as President by the servants. He is actually very intelligent, graduating from Cambridge University at the age of 12, but only because he hated studying so he wanted to get school over with early. He runs a successful corporation that focuses around his childish ideas (later based on his friends) to create cartoon characters. However, out of all the ones he has made, he believes they aren't nearly as good as Nyanmaru. He is currently staying at the Student Council President's house after his house was completely destroyed. Yuuki is a free spirit whom nobody can ever control.

Appearance
Yuuki has dark red hair. His hair is wild, going spiky in the back but splits to two sides to cover his ears. He usually wears a long-sleeve white jacket hoodie with black combat boots. Most of the time, Yuuki wears plain grey pants with a loosley tied belt. When not in battle, Yuuki wears a black shirt with tan pants. He has a barcode on his chest, revealing his origin as a specimen of a barcode project of Eden where they tried to create genius youths with incredible abilities.

Although his true age is unknown, it is implied that he is the youngest Code:Breaker. Meaning that he is under the age of 16, yet, it is also revealed he is over the age of 12.

When angered, his skin turns red, indicating he is going to use his sound guard, Scarlet Phoneme, around himself.

His Lost Form is a red cat with simple, black eyes, but he keeps his necklace on.

After the invocation of the Voice of Life, Yuuki has long white hair with long fringes and a more muscular and adult-like body, and he noticeably grows to be Yukihina's height. However, his mental age does not change with his appearance.

He is always seen wearing a hoop necklace with a small vial containing medicine dangling off it. It stays with him even if he changes into his Lost Form.

Personality
A major love of his is the Nyanmaru toy franchise. Despite his violent tendencies, he genuinely rewards kindness, and apologizes for his actions by giving gifts to people, although the gifts tend to be Nyanmaru merchandise. Yuuki has mistaken Sakura as Nyanmaru when her defense of Ogami reminds him of the animated character; as such, he calls her "Nyanmaru" instead of her name.

At first glance, he seems pretty calm and childish but goes on a rampage if anyone insults or soils Nyanmaru; Ogami Rei describes him as the "most barbaric Code:Breaker": "He'll attack both friends and enemy alike... In other words, Yuuki is the most barbaric Code:Breaker." When he turns into his Lost Form, a small red cat, he still retains his rage and his ability to speak, even going so far to attack anyone who makes fun of him in that form. He is also known to be very bad mouthed in his Lost Form. This form could be one reason why he is so fond of the anime character Nyanmaru; another could be because Nyanmaru seems to be friends with everyone.

It has been said that the way Yuuki acts isn't his "True Self". It might be that Voice of Life is Yuuki's true self as it is a peculiar gene of a special character embedded into him. Rui Hachiouji also thinks Voice of Life is "a supreme being" and like "a deity." But, if the "True Self" has something to do with personality, then it could be the fact that Yuuki has become fond of others than Makoto and Shigure during the series. Like Heike Masaomi, he too seems to not prefer the idea of killing, as he went out of his way to save a pregnant woman and a small child from an explosion. Nevertheless, he hates Heike and unlike the others, he doesn't fear him, going so far as to pour tea on his head. Still, he comes to help Heike when the young man is in battle against Saechika Hachiouji, stating Heike is the only one he accepts as the Second among Code:Breakers.

He has suffered a traumatic past, resulting in him becoming kind rather than evil. Yuuki usually protects others from danger, no matter what, and tries to help them in any way he can (though his ways are usually a little odd).

He hates Eden, but has joined the organization so that he can take it down. That hate is also the reason why Yuuki has to stay in touch with Eden.

When drunk Yuuki becomes depressed and comically refers to himself as a failure that can have no friends while crying.

Background
In chapter 94, Yuuki, Makoto, and Shigure used to be best friends and played together. However, due to an accident, Makoto was put into intensive care.

In chapter 99, other children avoided Yuuki's uncontrollable sound waves and called him "evil" and a "deadly weapon". When children escaped from the boy, they stomped on some tulips. He mounted a plaque for the purpose others would not do so again; that was when Makoto met him for the very first time. Makoto told Yuuki he was so kind, strong and amazing while he worried about flowers like that. Yuuki was surprised there was someone who was not scared of him, but Makoto just said there was no reason to be since Yuuki was an "amazing guy". Makoto called Yuuki, "Yu", and said he was happy to be Yuuki's friend.

In chapter 104, Makoto ran to Yuuki and appeared shocked when he understood Yuuki had jumped off the cliff just because of a dog; Yuuki simply answered the dog had been in "serious danger". Shigure hit Yuuki and the boy angrily demanded to know why it was wrong to want to save a dog. Shigure just answered by saying that if Yuuki did not know that, he should not talk to him. Makoto explained to Yuuki that Shigure was just worried about him because he was Shigure's precious friend; Makoto also added he felt the same way about Yuuki.

In chapter 105, a flashback of Yuuki showed that he was about to help some injured people in an accident. Yuuki was persistent on saving those people despite resistance from Shigure and Makoto. He used his sound powers to help people. However, a huge chunk of debris almost crushed him, only to be saved by Makoto who pushed him out of the way and sacrificed himself. Makoto, barely alive, was taken in by Eden to be treated. This caused Yuuki to stop making friends and spending his time with his powers to save Makoto, saying that is his resolve for being a Code:Breaker.

Yuuki (in Lost Form) and some other cats were protected by Ogami in an explosion. It was the first time they met; Ogami had taken down a villian who still had power to fight back and he threw a grenade, causing the explosion. Yuuki and other cats had come so near to see that bad guy that they would have been in big trouble without Ogami shielding them. Yuuki told Ogami he was the third Code: Breaker and he had wanted to see how the newbie was doing. Ogami threw the cat down from his shoulder and said Yuuki should not get intimidate with him and that one should pursuit one's goal alone. Yuuki told he liked Ogami's resolve and added: "... Hey, sixth. It's not like I'm gonna be friends with you, but... I seriously am taking a liking to you."

Meeting the Re:Codes
He first appears in chapter 35, playing a Nyanmaru crane game and winning all of the toys. When a staff member attempted to tell Yuuki to take the toys with him, Yuuki asked him what kind of flame was the best, to which Yuuki responded that blue flames were the prettiest.

Sakura Sakurakouji noticed him when he had fallen on the shop floor with many Nyanmaru toys, and offered to call an ambulance for him, only for Ogami to ask Yuuki why he was there. Yuuki asked Ogami to treat him something since he was hungry, and they got an opportunity to speak for a while during his meal; Yuuki reveals that he hadn't eaten in three days, forgot where he lived, lost his wallet and gave his phone to a stranger (just because that old man said he wanted it) and spent the rest of his money on a crane game. The boy said that he had a souvenir for Ogami, but fell asleep before he could say what it was. When he was about to give Sakura a Nyanmaru doll for her concern for his well-being, a man with his friends shoved Yuuki down before he could give it to her. When Yuuki noticed that coffee had stained Nyanmaru, he punched the man down and threatened to kill all of them one by one. He even punched Toki Fujiwara, as Ogami told Sakura that Yuuki was the "Barbaric Code:Breaker".

In chapter 36, he gave all his Nyanmarus to Sakura in his anger before starting eating again. There were many Nyanmaru posters and merchandise at the restaurant he was in, and he was eating so he could earn coupons for Nyanmaru merchandise. He attempted to get a golden Nyanmaru toy for Toki as compensation for beating him up, even though the latter didn't want it. Upon discovering that a little girl had won the last golden Nyanmaru doll, he was so furious, he was about to attack the little girl who "was planning to doom his life." The boy apologised for not getting the golden Nyanmaru and tried to give Puppy to Toki instead. Yuuki asked Ogami how much longer he was going to wear the ring on his finger and said after that: "Ah, that's right. 'That guy'... gave that to you, right?" After that, he remembered his souvenir and told Ogami that "the one Ogami was looking for" was returning. The boy also told there were many dangerous people in the country once again because of the person Ogami was searching for and suspected that: "... This place will once again become hell. Many people will die... Just like before ..."

In chapter 37, he watched as Lily and her mercenaries fought with Ogami. After Lily destroyed the restaurant, Sakura found herself outside with a pregnant woman and her daughter (the same one who had won the Golden Nyanmaru), with Yuuki carrying them. Toki thought Yuuki would get angry because the Golden Nyanmaru was broken but Yuuki just checked out the woman and her daughter; he was relieved when he noticed they were unharmed. After that, Yuuki said Toki should fix the Golden Nyanmaru.

In chapter 38, Yuuki was singing the Nyanmaru song and when Sakura told they should find Ogami, Toki just replied they could leave Ogami alone. Toki and Sakura argued about life's value and upon seeing Sakura's resolve to find Ogami, Yuuki aided her in tracking Ogami down with the help of his hearing. When Sakura shoved Ogami out of Lily's way, for the sake of saving people, Yuuki was reminded of Nyanmaru and vowed to protect her, defeating Lily with his Sound powers. When Yukihina knocked Lily out, Yuuki said that he was very strong.

Pursuing Code:Emperor
In chapter 94, Yuuki was trying to find Ogami with his Sound powers, but he could not. Shigure insulted Yuuki, but Toki defended him. Shigure reminded Yuuki that his foolish sympathy only killed people, "as with Makoto," to which Yuuki retorted that Makoto was still alive, as Shigure insisted that Makoto was already dead and it was Yuuki who took him away, causing Yuuki to run away. Shigure called him "a wimp," but Toki said he was not going to betray them since although hates Eden, he has never once left work undone.

Yuuki went to the hospital to see Makoto, telling him he should not worry, as he would be fine under Eden's care, since Eden's medical care is 50 years ahead of anyone else, so they would certainly make Makoto feel better. He said he was on a hunt after the "Blue Flame", and he would take down the bad guy so that Makoto would get a right to test a new medication before anyone else. He told Makoto that Shigure was waiting for him to awake, too, so that the three could play together again.

Toki said that Yuuki should just leave Ogami to him, since he could not possibly hunt down his "beloved sixth." However, Yuuki just glanced him coldly and Toki got a little horrified because of his blank expression. Yuuki just touched his necklace and left, ignoring Toki's question of what exactly happened between him and Makoto.

He attacked Kibou High, shattering the windows to draw Ogami out. When Sakura attempted to intervene, Yuuki just kicked her so that she was thrown on the ground, scowled at Ogami, and commanded him to give up his arm already. Sakura still had some power to hang on Yuuki's leg and beg him stop; after that she screamed she would not let that battle happen. She also questioned the boy's reason to fight; he answered he had someone he had to save and he would not care about any lives or sacrifices. Ogami had enough of Yuuki's reasoning and punched him, telling him that Yuuki, too, had become trash and got ready to burn him down.

In chapter 99, Yuuki attacked Ogami, and the invisible voice could not be evaded; although Ogami hit him, Yuuki was not seriously injured. Ogami told him he was horrible when using another person as a reason to hurt others, but Yuuki said Ogami would not understand, because he could kill his own brother like it was nothing. The boy also mentioned he could hear Makoto's weakening heartbeat which said it wanted to live; he also said he could not bear with the sound getting weaker every day. Yuuki shouted he would do anything to protect Makoto's life and attacked Ogami. Just then, Ogami and Sakura's classmates wandered outside, trying to warn Ogami of thick fog. They barely avoided Yuuki's sound waves and saw the furious boy hovering over them. Ogami tried to fix the situation by lying about some movie making project, but Yuuki attacked him while he had undone his flame because of his classmates. Maeshun hit Yuuki so that he would stop hurting Ogami. Although he attacked them, Ogami's classmates shielded Ogami from him and shouted they would never move away. They were trying to make Yuuki see they and Ogami were friends because Ogami would always help them if they were in trouble; Yuuki did not care but attacked. Ogami protected all of them with his flame and told Yuuki he would never let him hurt them.

In chapter 100, Yuuki was along with the other members of the Code:Breakers and Sakura, going to the beach in summer. Suddenly, when they had arrived there, he lost his powers among others. He climbed on Toki's head, trying to avoid getting wet in his cat form. A big tide crashed into them and Rui saved them from drowning. The boy got hit along others when he stared Rui's wet body for too long. The next day, Yuuki got sunburns like all the others.

In chapter 101, Yuuki asked if Ogami's friends meant anything to him since he had not told about his powers to them. Ogami told they were complete strangers to him and attacked while shouting Yuuki should not do anything to them. However, Yuuki used his Scarlet Phoneme in order to protect himself from Ogami's attacks and to gain a greater power. He explained how his technique worked and told Ogami should give his arm to him. Youngsters asked who they were and the boy answered by saying they were Code: Breakers "who judge evil that the law can't." When Yuuki attacked with sound waves later, they hurt Ogami's classmates even though people were farther from him than before. Kouji explained that barely nothing was safe from Sound and that if it lasted for too long, it could be life-threatening.

Yuuki told Ogami he understood how much Ogami wanted to save the "strangers". He said that ever since he met Ogami, his heart was shaken over and over by him. He also admitted that Ogami is an idiot that he seriously loves. However, he was still determined to save Makoto and lunged against Ogami, demanding his arm. Ogami asked if they should go to hell together while attacking with his flame but Yuuki managed to rip his arm off.

In chapter 102, Yuuki wondered if Ogami's arm would be enough to save Makoto. Ogami died after that. Yuuki still thought things for a moment before reaching out for that arm. He happened to be too late, then; Sakura snatched the arm and screamed she would definitely save Ogami. Yuuki did not give up but attacked her as furiously as before with his sound waves. He saw his attack was for nothing and mocked Sakura a little bit because she is a Rare Kind person. Sakura questioned him since she was sure Ogami was the person Yuuki liked the most. This angered him, telling her that it wasn't the true Yuuki, and moved to attack her. However, the other students came between them, vowing to protect Sakura and retrieve Ogami's arm. Yuuki was astonished and asked why they did come back; he became enraged because the youngsters did not honour Ogami's feelings and still claimed to be his friends. Students were trying to hold him off and explain they just did not want Ogami end up dead, but the boy still managed to punch a guy named Dekasugi hard. Yuuki lost it and screamed how his feelings towards Ogami were a whole lot stronger than theirs; at the same time, he remembered times with Okami and Makoto, too. He made a fierce attempt to get the arm when it suddenly released huge flames towards him.

In chapters 103-104, he noted that Ogami wanted to protect the students so badly that his soul did the work even if his body was dead. The boy attacked Ogami with Noise Crush when the latter had come alive again. Nevertheless, Ogami burned his sound and he said that pitch black flame was interesting. Yuuki once again criticized Ogami's actions and attacked, but Ogami was able to burn his Sound with his flames. When Ogami defeated Yuuki, he told Yuuki that the boy was better being carefree and like "Nyanmaru". However, Yuuki suddenly started writhing in pain, revealing that he had eaten some of the medicine in his necklace.

In chapter 105, Ogami and Sakura became concerned for Yuuki's health, only for him to stated that "everything's just starting." The two restarted their fight, only for Yuuki to try to give all of his powers to Ogami using Sound Life, saying Ogami was the only one able to help save Makoto and everyone else, while Yuuki was not able to hurt Ogami or anyone else anymore. Yuuki released a huge sound wave, alerting Toki, Heike, Shigure, and even Makoto. However, before he could give away all of his powers, he was stopped by Sakura, who refused to allow him to die. The girl demanded to know why the boy was trying to kill himself. Yuuki said he was worthless and could not protect every precious person only by himself. Sakura said, almost angrily, that friends were for that reason and Yuuki should have told them about his situation since she and Ogami were ready to be his friends. The boy was shocked when Sakura hugged him and cried how humans were weak, had they special powers or not: "The hands of one person can take up no more than another person... That's why we treasure our friends who can help us... Protect everyone." Nevertheless, Yuuki pushed her away and told that was not acceptable because Makoto was suffering all alone, still. At the end, Yuuki heard Morse Code from Makoto himself, telling him that he realised Yuuki is really a kind-hearted person and hoped Yuuki would bring more friends to visit him (Makoto) next time: "I love how kind-hearted you are, more so than anyone else. Come visit me with more friends next time, ok?" Yuuki probably started to cry after hearing this with Sakura and Ogami smiling. Makoto continued: "You're my proud friend. Stay with me. Forever and ever, alright?"

In chapter 106, Yuuki apologized to Sakura's classmates for attacking them, and then prepared to be killed by Ogami. However, Maeda interfered, punching Yuuki, saying that he would be haunted if Yuuki died without explanation. When they decided to forgive Yuuki, he began seeing them all as "Nyanmarus".

In chapter 107, Code:Emperor confiscated Yuuki's Sound as payment for Belphegor when the Sound protected protected Ogami by covering him with the Scarlet Phoneme when Code:Emperor attacked Ogami. Yuuki explained that happened because he put his sound into Ogami; the boy also added the Sound seemed to like Ogami and hate Emperor. Emperor smiled haughtily and said the special power did not know its place. When Heike attacked, Yuuki protected Sakura's classmates and was badly injured. He was removed from battle by Kouji.

In chapter 113, he left to train with Shibuya. He returns in chapter 118 to confront Toki and prevent him from getting to Ogami. In a heated battle, Yuuki initially gains an upperhand with his Echo attack, but Toki eventually overpowers Yuuki and defeats him. Kouji managed to recover Yuuki and brought him to the hospital.

Infiltrating EDEN
Despite his wounds, Yuuki goes with Ogami and the rest to find Eden's headquarters, led on by Lily. Because he was too weak to move properly, Yukihina voluntarily carries him on his shoulders. The two instantly bond through their mutual dislike of Heike Masaomi. Yuuki notes that Yukihina sounds more as if he was Heike's long time friend, but was then distracted by the coldness of Yukihina's body. Ogami remarks that Yukihina must have taking a liking to Yuuki's naivety, as he rarely talks about himself. He also adds that despite having known Yukihina for so long, he doesn't know what happened between him and Heike either. After coming to the graveyard and Sakura awakens as the Rare Kind, Yuuki loses his power and transforms into a cat again. He's on standby during the entire battle between Ogami, Toki, and Fujiwara Nenene.

Kibou Festival
In chapter 148, Yuuki triumphed over his trial of the Kibou Festival by overcoming his wrath easily. Since he aware of his own weakness. However, he did not gain any new strengths nor any of his original power that he gave to Ogami. Later he played with Sakura after the trial. Yuuki is the first person overcome his trial in Kibou Festival during night.

Infiltrating Eden: Part 2
In chapter 159, while protecting the Cross Marks from Utah the Mirror, Yuuki gains a new ability, Voice of Life, thanks to the influx of power from them, making him more powerful and changing his apperance to a grown-up version of himself. This new power enabled him to destroy Utah with a single attack. It was hinted by Utah (shortly before his death) that Yuuki might be the "Forbidden Fruit Apple of Eden". It is unknown at this time what exactly that entails for Yuuki.

During their encounter and subsequent battle with the Code:Names, Yuuki jumped in Heike's battle with Saechika, along with the rest of the Code:Breakers, in order to help him, stating that while he hated him, he also accepted him as the only one who can stand above him. Afterwards, he fought against Shigure and his subordinates, until the arrival of the Rare Kinds interrupted them.

The Angels
Yuuki, like the other Code:Breakers, is currently fighting against the Angels and has been present for a majority of the battles. He was also the first to hear the name 'Angels' in chapter 170.

Out of the Angels, Yuuki bears the most resemblance with Cat Boy as both appear to be the youngest of their groups and have similar hair styles.

Anime
In the anime, Yuuki first appears in episode 2, confronting Hitomi. When he attacks Hitomi, however, Yukihina defends Hitomi. After a brief exchange of attacks, Yukihina and Hitomi retreat.

When Ogami succumbs to his Lost state in episode 6, Yuuki is seen using his Sound to jump through the air, stating "06! I came to save you!" He proceeds to battle Hitomi's agents in Ogami's place. After knocking the agents down, he is interrupted by Heike, who tells him that his methods were "too crude," and the latter proceeds to completely destroy the corpses of the agents.

In episode 7, Yuuki is seen watching Nyanmaru saving other cats. He is then seen with Heike, Kanda, Ogami, and Sakura, where he is revealed as Code:03, the one who uses the power of Sound. They later go to Sakura's house, where he found Toki with his power. He is shown briefly battling with Hitomi, but is defeated and turns into his Lost form.

He converses with Rui after the battle, and splits up with the other Code:Breakers sans Heike to look for Hitomi, without any success. He stumbles upon the battle between Heike and Rui, and watches with alarm as Heike knocks Rui unconscious.

Later, he finds Ogami who is searching for Sakura. He explains that Heike has betrayed them and they go off to find Sakura. He later finds Heike but he escapes after a brief fight.

Sound
The ability to control, generate, and manipulate soundwaves. With it Yuuki is able to increase sounds, for example when Yuuki uses his power, it allows him to increase the sound of his voice to be so powerful that it can create craters and move heavy objects. Yuuki is also able to increase his speed to incredible levels to the point where he is able to move at the speed of sound. Yuuki also has a drastically enhanced sense of hearing, enough that wate in his ears sounds like rushing boulders, making it a very useful ability for detection. Later on Yuuki is able to hear the "Voice of Life". He's even able to use his sound to protect others. Also because all objects vibrate at a certain frequency, Yuuki is able to match that frequency to make the object shatter. After saving the Cross Marks, Yuuki showed the ability to create holographic images using "Ultra-Sound Imaging". Yuuki keeps his powers down very often due to his emotions being able to control how much his power output is, so if he seems "normal" his power will be under control, however if he is "lazy" or possibly "disorientated" he is unable to control his power whatsoever and can cause great damage. When enraged, Yuuki actually changes as his hair becomes totally black and his skin turns red as well.

High Intellect: Despite his rather odd and unusual behavior, Yuuki has been known to be extremely intelligent. He graduated from the famous Cambridge University at only 12 years old, which literally is amazing as there are no known people (even among high status) that are are able to graduate at such a young age. It was revealed in chapter 148 that Eden made Yuuki by using the genes of intelligent people and power users. When he was younger, he was already doing high-school level studying.

Skilled Hand-to-Hand Combatant: Yuuki has been shown to have great skills in melee combat as he was able to smash two thugs simply by knocking both of them out and even beat Toki till he flew in mid-air.

Techniques

 * Yuki_Code.gifSpeed of Sound: Yuuki's primary ability is his immense speed which has been acknowledged by many to be his most important skill. He has been able to avoid almost any attack thanks to this ability. It can be also used offensively as he can sneak attack his opponents before they can even react. He can also use his speed to create afterimages of himself, as shown in his race with the Rare Kind Cat Boy.


 * Sonic Sew: Yuuki forms soundwaves around his hand and uses their high frequency to pierce his opponents.


 * Noise Crush: Yuuki places his hand to the ground and causes vibrations to form, and then destroy the ground.


 * Yuuki_and_Scarlet_Phoneme.jpgScarlet Phoneme: It is a stronger form that Yuuki develops by creating high density frequency around his entire body; his skin turns scarlet red, pupils turn black, irises turn yellow and his hair turns white. He is able to emit sound around over his body automatically without him being the one emitting it. The sound waves are so dense that they vibrate through the ground to the point where he is able to cause great damage to Kibou High school (despite the fact that the school was covered a great deal with Shibuya's blood). He appears to have increased both his offensive and defensive capabilities as he explained to Ogami: "I use very dense and high frequency sound waves to shelter my body, revitalizing it to its max. Since I'm inside this shell, even if you want to burn me, your blue flame will never reach. In other words, nothing's going to work on me, nor can anything stop me now. I can't hold back anymore, either." However in chapter 104, Ogami managed to burn off his Scarlet Phoneme with his Belphegor.


 * Sound Life: Yuuki gives his powers to someone else. It seems to make him bleed and gradually lose his life if he is not stopped before finishing.


 * Echo: In chapter 124, Yuuki used this technique to stop Toki from going after Ogami's arm. Toki explains that it: "You used 'Echo' didn't you? In this underground tunnel, it's easy to create an echo using a single sound. The echo multiplies and bounces back to you, As you absorb them to multiply your power. How your drawings sing along is due to echos coming from several directions...like on the mountains." While this echo makes Yuuki faster and gives him a boost in power, the effects it has on his body are dangerous.


 * Million Phoneme: Yuuki uses high-frequency sound waves to create a defensive barrier for repeling enemy attacks. He used this power in chapter 159 to shield the Cross Marks from Utah's attack.

Makoto
Yuuki's friend who made a form of morse code for him. Makoto was fatally injured because of Yuuki and in atonement, Yuuki decides to work for Eden for Makoto's sake. Because Makoto was constantly suffering, Yuuki believed that he didn't deserve friends and held everybody at a distance. Makoto, however, wishes for Yuuki to be happy, and tells Yuuki so through Morse Code. Yuuki often refers to Makoto as "my precious Makoto".

Shigure
They were once friends in the past, and they lived in the same facility since they were both part of the Barcode Project. Shigure found Yuuki's actions to be reckless and occasionally hit him because he was worried that Yuuki might kill himself one day.

After Makoto fell into a coma, they grew distant; Shigure considers Makoto to be "dead", and blames it on Yuuki. He states that Yuuki was the one that deserved to die first, out of all the Code:Breakers.

Rei Ogami
Yuuki greatly admires Ogami and finds him very kind. In chapter 101, it reveals the past of Yuuki and Ogami. Yuuki (in his Lost Form) and some other cats were protected by Ogami in an explosion. It was the first time they met. Yuuki stated that ever since he met Ogami, his heart was shaken over and over by him. He also admits that Ogami is an idiot that he seriously loves. Yuuki had never accepted anyone else but Makato and Shigure as his friends, but in chapter 106, he also accepted Ogami and Sakura.

Ogami also cares for Yuuki. He lets Yuuki do what he wants and is rather protective of him. Ogami also acknowledges Yuuki's brutal side, telling people to be cautious. Yuuki is able to do things that nobody else, besides possibly Sakura, can do, such as snuggling up to Ogami while in his Lost Form, which Yuuki did in their first meeting.

Yukihina
Yuuki takes great interest in Yukihina, nicknaming him "Yukinko". Both of them dislike Heike, although for relatively different reasons. In Chapter 129, Yuuki is the first of the Code:Breakers to discover that Yukihina's body was ice-cold, which Yuuki found to be "so cool". Ogami notes that Yukihina must have taken a liking to Yuuki's naivete, as Yukihina rarely spoke about himself. Yukihina often acts as Yuuki's guardian afterwards, watching over Yuuki and controlling Yuuki's childish impulses.

Toki Fujiwara
Though he thinks of Yuuki as immature and childish, Toki is somewhat friends with him. When in their Lost Forms, Toki usually carries Yuuki around, signifying a slight friendship between the pair.

Rui Hachiouji
Yuuki finds Rui a kind and caring person. Rui, knowing how childish Yuuki can be, tends to show more concern for him. Such as in chapter 152, when Yuuki ran off after stating he took his sound power for granted, she was rather alarmed and somewhat worried about his feelings.

Heike Masaomi
Much like Rui, Yuuki appears to dislike or at least distrust Heike the most and doesn't seem afraid of him. He once even went as far as to pour tea over his head when Heike ordered him around. However, Yuuki has revealed he has accepted him as Code:02, "the one who stands above the third"

Trivia

 * His lost form is, similar to Kouji, an animal type. Interestingly, they both also have similar numbers in their group
 * He can sleep with his eyes open.
 * He has a scent of warm milk, mentioned by Sakura in chapter 52.
 * He says that he refers to his 'friends' with numbers, but in reality he makes up nicknames for everyone to keep them at a distance. Sakura is "Nyanmaru", President is "Nisemaru", Ogami is "Sixth", Toki is "Fourth", Heike is "Second", Rui is "Ruirui" or "Fifth", and Yukihina is "Yukinko". After acknowledging that Ogami is really his friend rather than just a fellow Code:Breaker, he calls Ogami by his name and becomes closer to everyone else. He becomes especially attached to Yukihina.
 * He becomes depressed when he is drunk, mentioned in a special chapter.
 * In the anime, he makes his debut before Toki, whereas in the manga it was reversed.