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"...
Haruko is the leader. 
She told me to take over.
Haruko ist hier die Anführerin
und sie ist es, die mich gebeten hat.
Haruko es la líder. 
Me dijo que me encargara.
Haruko es la líder. 
Me dijo que me encargara.
C’est Haruko la chef.
È Haruko il capo.
Ha detto che devo occuparmi di te.
A Haruko é quem manda. E ela
mandou eu cuidar de você.