Kareshi Zettai Korosu Kanojo vs. Kanojo Zettai Otosu Kareshi

There were two opposing high schools.
The goal of the girls of Tamadori Girls High School was to pretend to be the girlfriend of the boys of Kaishu High School and kill them in their sleep. The goal of the boys of the Jade Bird Girls High School is to make the violent girls of the Jade Bird Girls High School fall in love with them and make them their true lovers.
For the sake of the school's honor, a boy and his girlfriend are competing against each other...

(Source: Kodansha, translated)