This nameless man works as a teacher at Iwatobi High School, but it is unknown which subject he teaches.
He is a strict-looking, middle-aged man with short, brown hair and purple eyes. He is sometimes seen wearing a white shirt with a pink sweater over it.
The male teacher is stern when it comes to the discipline of his students. He scolds Haruka Nanase, Makoto Tachibana and Nagisa Hazuki twice (though, Haruka gets away once) for entering their old Swim Club and Samezuka Academy's indoor pool, calling the act illegal trespassing.
This character appears to be a disciplinarian and often chastises the boys when they break the rules. His planned punishment is usually softened by Miho Amakata's intervention, which consists of reciting strange quotes from literature which she believes pertinent but which he never understands, but finds annoying. When he chides Haruka, Makoto and Nagisa for the second time and Miho tries to help them by saying yet another "famous saying" related to fish, he immediately interrupts her, saying that he hates fish, causing Miho some awkward feelings.
As colleagues, this teacher and Miho Amakata seem to have a pleasant and professional relationship, though he is often irritated by her habit of quoting great figures which, in turn, makes the both of them feel awkward and causes him to deride her for doing so.
- He doesn't like fish.
- Rumor has it that he is scared of Miho.