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"...
It took me a month just to be 
able to get close to them.
Ich habe einen Monat gebraucht,
bis ich mich ihnen nähern konnte.
Me tomó un mes hacer
 que se me acercaran.
Me costó un mes conseguir
 que se me acercaran.
Ça m’a pris plus d’un mois
pour me rapprocher d’eux.
Io ci ho messo un mese solo ad avvicinarli.
Eu demorei pelo menos um mês para
conseguir chegar perto desses dois.