Having come to Canada upon hearing the fake news that his biological mother Haruko is in critical condition, high school student Kaidou Haru meets a young boy named Ren. "You have a new brother. Take care of him." So instructed by his mother, Haru is forced to spend the summer with Ren. Every day is a battle with Ren, who refuses to listen to anybody. However, as Ren grows to like Haru little by little and Haru comes to adore Ren as well, they make a certain "promise"...
Great! It's a promise!
Juhu! Abgemacht!
Genial. Prometido.
Genial. Prometido.
Génial !
C’est une promesse !
Ottimo! È una promessa allora!
Oba! Me prometa que vai!