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"...
I happened to be at the orphanage 
with the dogs on a sympathy call,
Ich war mit den Hunden bei einem
Krankenbesuch im Heim.
Pasé por el orfanato con
 los perros por caridad
Pasé por el orfanato con
 los perros por caridad
Parfois,
en promenant les chiens,
Ero andata per caso in visita
 all'orfanotrofio con i cani
Um dia, fiquei de levar os cachorros
em um orfanato para um trabalho voluntário.