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"...
I wish she'd be nice to me, too.
Wäre die doch
auch zu mir so nett.
Desearía que fuera buena conmigo.
Aunque ojalá fuera buena conmigo.
Ça lui arrive d’être gentille
avec moi aussi.
Mi piacerebbe che fosse buona
anche con me.
Só espero que ela seja 
 gentil comigo também.