Kyoushi

He was one of Professor's classmates, nicknamed "Teacher" for his friendly personality and tendency to give good advice. In a diary entry, the Professor mentions them living next door to each other, attending the same school from elementary to high school, and competing in test scores. Although Professor is aware of his own jealousy towards Teacher for having many friends, he eventually recognizes traits of his own personality in "Teacher", which, ironically, leads to drifting away from him.