Shishunki ni wa Me no Doku desu

Shibata, who's not too bright, doesn't get along with Mitani-san, who is handsome but stoic and expressionless. However, after getting a zero on a test, Shibata ends up taking remedial classes from Mitani-san! At first he didn't want to go, but when he sees the teacher's smiling face and gets to know a different side of him, he begins to enjoy the time with Mitani-sensei.

(Source: MF Fleur, translated)

Note: Includes an extra chapter.