Koisuru Psycho no Shirayuki-kun

I will kill everyone for your sake.
"Hey, I think I like you!" Shirayuki says with a smile.
Haruki endures relentless bullying from a trio of classmates. One day, a beautiful transfer student named Shirayuki suddenly approaches him and asks if he would date him if the bullying stopped. Haruki dismisses it as a joke. But the next day, one of his tormentors disappears. Then another. One thing's for sure—Shirayuki is a psychopath that lacks common sense and empathy.
(Source: taskey, translated)