春夏秋冬代行者 百歌百葉 raw 第01巻 [Shunkashuto Daiko Sha Hyaku Uta Hyaku Yo vol 01]

The novels take place in a world where the only season is Winter. Winter lives a lonely existence, and so they create Spring. A short time later, due to the wishes of the land, Summer and Fall are also born, and the four seasons are complete. The human children in charge of bringing in the new season every three months are called the "Proxies of the Four Seasons."