|Anime debut||Episode 3|
|Manga debut||Chapter 5|
Mr. Matsuyama is a teacher, who was temporarily replaced by Ryoko Tamiya.
He didn't make an offical appearance in either anime or manga series.
Nothing is known about his personality.
Mr. Matsuyama is first mentioned during a school meeting in the auditorium. It's stated that he was in a car accident and is currently in the hospital. He was replaced by the parasite known as Tamiya Ryōko.
It's unknown if he returns to his teaching position after recovering.