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'll make dinner, so go wash your han—
Haré de cenar. Ve a lavar…
Haré de cenar. Ve a lavar...
On va bientôt manger,
va te laver les…
Ora preparo la cena,
perciò vai a lavarti le ma—
Já vamos jantar, então vá lavar as mãos—