Because you like Light Yagami in Death Note
Yuri is living in the afterlife, which takes the form of a high school where no one dies. But if you follow the school's rules and live a "normal" life you vanish. See them in Angel Beats!.
Undercover as an average high school student, Kallen Stadtfeld is actually most at ease when the action's fast, furious, and dangerous. See them in Code Geass.
Suzaku Kururugi defeats enemies with his flashy but deadly jump kicks. But he's willing to sacrifice himself for peace. See them in Code Geass.
Lelouch vi Britannia is a high school student by day, masked destroyer of tyrannical empires by night. See them in Code Geass.
If there's power in being average, Mikado Ryugamine will find it and use it. See them in Durarara!!.
Yukiteru is a reclusive observer who would rather watch life go by than participate in it. See them in The Future Diary.
Impassive, overly literal, and a little short on people skills, Angel dedicates her life to enforcing the rules. See them in Angel Beats!.
Sebastien Michaelis is a demonic butler who approaches life with effortless finesse and a diabolical streak. See them in Black Butler.
An obsessive schoolgirl, Yuno has two sides to her personality, and both are equally unnerving. See them in The Future Diary.
For somebody who won't answer questions, the enigmatic C.C. sure asks a lot of them. See them in Code Geass.
Yuki Cross is a cheerful, funny, bold young woman with hidden insecurities. See them in Vampire Knight.
For the sake of science, Kurisu Makise will persevere no matter how deep into the dark secrets of the world she finds herself. See them in Steins;Gate.