Code:End

Code:End is a phase in a Power User's life where their power has exhausted itself and destroys the power user's body. Hitomi explains as a Code:Breaker uses their power, it will eat on the user until they die.

Hitomi was the first person in the series seen to reach his Code:End, while fighting Ogami for the life of the prime minister; presumably, the clocks on the wall represent all of those who have met their Code:End as well.

Saechika Hachiouji began succumbing to his Code:End, but was killed by Kagerou before it could happen.

Trivia

 * Although using their powers will cause them to die, it seems as though controlling the source of the power, the Force of Life, can cause a user to delay or completely avert reaching his/her Code:End. This is seen in Heike, Sakurako, Code:Emperor, and Kouji.
 * Presumably, being an undead will also avert one's Code:End, as seen in Yukihina.