Rebirth Knight

Rebirth Knight (리버스 나이트) is a shounen manhwa created by Jae-Beom Yu. It is serialized in IQ Jump.

Plot
Kang Chan, a high school student meets a girl and immediately falls in love with her. What he doesn't know is that the girl is a secret agent that deals with some mysterious masked men who try to conquer the Earth. The group where is belongs too is called "Rebirth Knight". As soon as Kang finds out the truth, he gets amazed and wants to join as well.