After dedicating his life to the criminal organization, Glory Club, Peter retired from his status as a legendary assassin and spent his remaining days running a quiet second-hand bookshop. However, after being ambushed one day and nearly killed by the organization he dedicated his life to, Peter found his body miraculously returned to his teenage years. Now, with Peter back to his peak physical condition, he is determined to resolve the issue with Glory Club.

The betrayed old assassin has been rejuvenated

But... no one recognizes him.

Now his name is Kim Sun-Gu and he is hiding his true identity as Peter.

Sun-Gu enters the New Honor High School as a transfer student, the place of the Glory Club killers. School to train killers, Sun-Gu intends to seek revenge on Glory Club from within.

As he enters the school, his charming, tall and handsome appearance attracts the attention of many girl in the school.