Koisuru Kichikujima

The manga is a school romantic comedy spin-off of Hokazono's Kichikujima manga. The manga casts the original manga's serial killer Kaoru as a high school girl who falls in love with fellow high schooler Takahisa, the protagonist of the original manga. As a member of the school's discipline committee, Kaoru is normally strict with the boys, but her feelings are thrown for a loop when she's in front of Takahisa.

(Source: ANN)