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"...
He responds when his name is called now,
Er antwortet dir, wenn du ihn beim
Namen rufst und er isst bereits am Tisch.
Responde cuando dicen su nombre
Responde cuando dicen su nombre
Il répond quand tu l’appelles
Adesso risponde
quando lo si chiama per nome
Ele passou a responder quando 
 o chamamos pelo nome