Batsu was once a hitman for an unspecified family within the Tojo Clan, infamous for snapping his victims' necks with his bare hands.
Eventually, his patriarch ordered him to assassinate a few leading figures within a rival family in exchange for a promotion when he got out of prison. Batsu carried out the hit and was sentenced to 15 years in prison.
When he was released after serving his entire sentence, he discovered that his family and their rivals whose leaders he'd killed had made a truce. Since Batsu's release threatened that truth, his own family betrayed him and tried to have him killed, though Batsu succeeded in killing his assassin and getting away alive.
Enraged, Batsu wound up joining the Reapers; a vigilante group determined to destroying the yakuza by assassinating as many of its members as they could get away with, along with any former yakuza who refused to aid them.
Batsu is the first member of the Reapers whom Kiryu fights as he tries to dismantle the organization for Ibuki and the Honest Living Association.
Kiryu encounters Batsu assaulting a low-ranking yakuza in the parking lot on East Taihei Boulevard. Kiryu rescues the young yakuza and sends him away while he fights a furious Batsu, who wields a sledgehammer in the encounter. Ultimately, Kiryu defeats Batsu and convinces him to leave the Reapers to become an honest civilian by joining the HLA.
In exchange for helping Batsu join the HLA, Kiryu is rewarded with 50,000 yen.