TONARI NO KUROGANE-SENSEI

Rika lived alone in her apartment. When she accidentally punched a hole in the wall, she found her strict, iron-masked teacher Kurogane-sensei on the other side! To keep quiet about all the personal "dark side" things she overheard from his apartment, Rika demanded extra tutoring from Kurogane-san!



(Source: LaLa, translated)