Arisawa Atsushi enrolled at Jougaoka High School believing his first love, Shibata Masami, was a teacher there. As it turns out, Masami no longer works at the school, but his brother Masayoshi has taken over as the school doctor. Since they look alike, Atsushi believes Masayoshi is actually Masami. It isn't until after he falls in love with Masayoshi that he discovers the truth. He resolves to grow up and be an adult equal to Masayoshi so that Masayoshi will reciprocate his love.

He was born in Tokyo, and is a sympathetic and caring boy who tells the world how he feels. He excels at academics and lives with his parents and a pet dog.