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"...
Were you playing in the river again?
Hast du wieder
am Fluss gespielt?
¿Jugabas en el río de nuevo?
¿Jugabas en el río otra vez?
Tu es retourné t’amuser
à la rivière ?
Sei stato di nuovo a giocare al fiume?
Estava brincando no rio de novo?