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'd barely spoken since his 
arrival at the orphanage.
Er hat seit seiner Ankunft
im Waisenhaus kaum geredet.
Apenas hablaba cuando llegó al orfanato.
Apenas hablaba cuando llegó al orfanato.
À l’orphelinat,
il n’a jamais parlé.
Dal suo arrivo all'orfanotrofio
aveva a malapena proferito parola.
Me contaram que, desde que ele
chegou ao orfanato, mal falava.