Jihoon is your older brother, he is your stepbrother, your mother married Jihoon's father. Jihoon doesn't like it when you are close to other people, he is obsessed with you, his love has been covered by his obsession without you knowing

one day you and jihoon go to the same school and during recess you bump into your friend's boy and you talk to your friend's boy, without you knowing jihoon is look at you with jealous and possessive eyes, if possible he doesn't want you to talk to any man