|Volume Number||Japanese Release Date||Japanese ISBN|
|1||28 July 2010||ISBN 978-4-04-854500-6|
|2||26 November 2010||ISBN 978-4-04-854562-4|
|3||28 June 2011||ISBN 978-4-04-854644-7|
|4||28 November 2011||ISBN 978-4-04-120074-2|
|5||30 August 2012||ISBN 978-4-04-120388-0|
|6||1 November 2013||ISBN 978-4-04-120900-4|
|7||1 August 2014||ISBN 978-4-04-101894-1|
|8||1 August 2015||ISBN 978-4-04-103300-5|
|9||30 April 2016||ISBN 978-4-04-104150-5|
The main protagonist Kaidou Haru had just arrived to Alberta, Canada all the way from Japan to visit his biological mother who was said to be 'on the verge of death'.
"It took over 9 hours to get here from Narita, and another 3 hours by car from the Calgary International Airport. This epic journey started after I received notice, just before my summer break started, that my mother was on the verge of death. I half-suspected it to be a joke - but of all things 'on the verge of death'??" — Haru KaidouOnce Haru arrives to his destination deep in the mountains of Canada, not only did he find out that his mother was healthy, but she had also 'adopted a new puppy'. This 'puppy' was actually an eight year old boy named Ren. At first, getting close to and educating Ren was a little difficult for Haru because Ren spent most of his time with the dogs. But even so Haru made it his goal to civilize Ren at the end of the summer. Their relationship slowly improves throughout that summer and the night before Haru sets off to return to Japan, he makes one important promise to Ren. The promise that they'd live together in Japan.
"So... Let's live together then! You're my little brother now, so it's fine!"
"...I'll think it over."
"It's a promise!"After his flight to Japan Haru gets picked up by his parents. But during their ride home, they crash with another car. Haru's parents tragically died and Haru was put under critical condition, suffering numerous fractures. He develops temporary amnesia due to shock from the accident and forgets everything he had done that summer.
A few years after the accident Haru is now healthy and works as a Host. One day after work his lawyer tells him to come to her office. She then introduces a boy named Ren to Haru who came to live with him because of a promise Haru totally forgot about. Haru also finds out that the Kaidou family formally adopted Ren three months before they died. Kaidou Haru, the eldest child now has the sole responsibility to care for Ren as his guardian.