Shinigami no Kikan ~Assassin~

Once feared throughout the underworld as its strongest hitman, Nightshade is a master of techniques that sever the nervous system and deprive his targets of all five senses. Known as a Reaper, he leads them to certain death—but his life as an assassin ends when he disobeys an order to protect a girl and is executed by the organization he served. Seventeen years after his death, Nightshade is reborn. He now lives as an ordinary high school student, far removed from his former identity as a feared killer.