The Narcissus-Like Event

His name is Benedict, a handsome and gentleman towards women. He is a heartthrob. Every girl in their school crushes him-not just because of his Apollo-look but also for his kindness and intelligence.
But...
...one day, a mysterious event suddenly happened...
Whenever a girl confesses her feelings to him...
that girl will be died a day after the confession.

Why all these things happen? What kind of mystery is covering the truth? Is Benedict has a curse...?
Is someone kills them?
Or...
Is Benedict kills them?