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"...
Where'd that stupid brat go?
Wo ist das Gör nur hin?
¿Adónde fue ese chiquillo?
¿Adónde fue ese mocoso?
Où il a bien pu aller,
ce morveux ?
Ma dov'è andato quello stupido moccioso?
Para onde é que aquele pirralho foi?