Teppei is Satoko and Satoshi's uncle/foster father. He and his wife were forced to take care of Satoko and Satoshi after the death of their parents, but they abused them. He currently lives in Okinomiya. According to Kasai, he is a pimp and uses his lover Rina to swindle men out of their money.

Spoiler

He is killed by Keiichi in Tatarigoroshi-hen and by Rena in Tsumihoroboshi-hen, in their attempts to protect Satoko and Rena's father respectively.