Satsuki's science teacher. Although aware of her penchant for trouble, which he constantly lectures her for, he doesn't hate her. He's one of the few people at school that hasn't disassociated from Satsuki, unlike most of her schoolmates, and even staff, showing he cares for her. He unknowingly contributes to the success of many of Satsuki's rescue stunts by constantly providing insightful information. In chapter 43, his name was revealed for the first time, as up that point he was only referred to as simply "Sensei".