Shimomura is a classmate and friend of Ayumu Aikawa at school, belonging to the same social circle as Taeko Hiramatsu, Yuki Yoshida, Kanami Mihara, and Tulio Orito. He readily assists Ayumu, such as helping him reach the nurse's office when Ayumu suffers from sunlight exposure due to his undead condition. When reports surface of a suspicious figure in the school cemetery, Shimomura joins Orito and others in the classroom buzz about the sighting. Later, he witnesses Ayumu's public transformation into the chainsaw-wielding magical girl and the ensuing monster battle alongside the entire student body, an incident that significantly damages Ayumu's reputation.