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"...
but you want friends, too, don't you?
aber er will doch sicher
auch Freunde haben.
pero también quieres amigos, ¿no?
pero también quieres amigos, ¿no?
mais tu voudrais
avoir des amis, non ?
ma tu vuoi anche degli amici, vero?
mas o Ren gostaria de fazer 
 amigos também, não acha?