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"...
You idiot! The river's over its banks!
Du Idiot! Hier ist Hochwasser!
¡Idiota! ¡La corriente es muy fuerte!
¡Idiota! ¡La corriente es muy fuerte!
L’eau monte, là !
Idiota! Il fiume è in piena!
Seu idiota!
O rio está cheio!