Tatsumi

Tatsumi built his career as a meticulous, respected detective, skilled at reading people and telling truth from lies — a talent that once made him a genuinely good man to work alongside. That changed the day he came home to find his wife murdered.

Consumed by grief, he tracked down and killed her attacker in a delusional rage, then kept going, hunting down criminals, letting them harm someone new, and executing them the moment their guilt was confirmed. What began as revenge hardened into a self-appointed crusade, and the same rational detachment that once made him a good detective curdled into cruelty toward the very lawbreakers he judged.

His pattern finally catches up with him after he watches a stranger assault the sister of a young man named Shimada without intervening — treating the crime purely as an opportunity — and is stabbed to death by Shimada in the confrontation that follows. He arrives at Quindecim still convinced his methods were justified, comparing his own judgments to the arbiters' work even as he refuses to see the resemblance to the killers he once hunted.