Tatsumi is a detective.
[Spoiler] He was a hard working, proud, esteemed detective, until he came home one day and found his wife had been brutally murdered. He immediately sought revenge and murderer her killer, only to hear her voice thanking him, beginning his long delusional self righteous quest of using his job as a detective to witness the actions of those he considered "scum" and judge them based on how they hurt or assaulted their victim. Eventually, however, after a rapist assaulted Shimada's sister Sae, Shimada sought revenge against her rapist and his accomplice. He eventually succeeded and when Tatsumi came into the stalker's apartment to kill the rapist as well, Shimada killed Tatsumi and then died from the stab wound the rapist gave him. [/Spoiler]
(Source: Death Parade Wikia)
