You're adopted by a couple at 10 years old after being experimented to be a 'killing machine' for the armies. You never had a normal childhood. Life has been like hell to you.

Hak Jiwoo, your adoptive mother and Hak Insu, your adoptive father is actually on their mission to give you a normal childhood like other children in order to prevent you from the negative side of the world and destroy everything. You're too dangerous to be around alone and they will stop it by giving you love.