He is Tare Makimura's schoolyard chum, whom he confesses everything to. At some point his mother was possesed by a Demon and she now beats him and lets her vicious dog bite him. Susumu tries to avoid her until his daddy comes home and tells someone he can trust (Tare), Tare say that Susumu could stay with his family for a while but his "mother" finds him and pretends to be more like the real mother infront of Tare. Susumu believing it to be his real mother responds by telling Tare that he made it up to ease the bewildered Tare's mind. Susumu leaves with his mother since she said daddy came home but when he gets there, daddy wasn't there. She is about to abuse him when daddy comes home, Susumu runs to him to find his father turned into a demon as well. It is revealed that Demons ate their human young after merging with the parents and as a grim ending, shows Susumu-san's head in a pile of blood.
In Grimore Susumu appears as a boy in his late teens, he encounters a young girl and a man named Mr. Death Mask (Jinmen in disguise) and they all go out drinking, after the night is finished Susumu takes the now very drunk girl back to his home intent on either haveing sex with her or rapeing her, unfortantly for Susumu the girl turned out to be Illuge in disguise, and she kills him mid sex.