Impure

Maki Sakura, a junior high school teacher has a reputation among her students for being a beautiful teacher, but she is in fact is an unfortunate woman who, despite her outward appearance, is overly masculine, likes to drink, and has no luck with men. However, despite knowing her true face, Shirou, a student who lives next door, has had feelings for Sakura since he was a child...

(Source: Shodensha, translated)

Note: Includes one bonus chapter