Tsuyoshi Shiga (志賀 剛司 Shiga Tsuyoshi) is the teacher advisor responsible for Nishiura High School's baseball team.
Though he is a math teacher, Shiga-sensei appears to have a great deal of knowledge about the body and how it works. He may not be knowledgeable on baseball-related stuff, but he gives lessons to the baseball team regarding improving their concentration and health.
He is the one person who Momoe actually may be intimidated by, as she briefly shudders when asked why she was reminding the team to focus on keeping their grades up.
- (To Abe) "...but I hear the battery is one in both body and spirit, right ?"