This is the second story of "The Lion Books" series. A boy meets a lonely little umbrella ghost wearing Geta. He promises the ghost that he will give it a pair of rain boots in exchange for three wishes. The boy, however, grows up completely forgetting the promise. One day, when he happens to remember the ghost, he rushes back to that bridge in his hometown, to the Rain Boy...This is a moving, sweet hometown fantasy about a gentle ghost and a forgotten promise.

Based on the game by Haikuo-Soft. A story about the reunion of 4 childhood friends, Yuzuki, Matsuri, Nono and Makoto, in their deserted old school campus, Mochitsuki Academy. 3 years ago, they buried a time capsule under a tree inside the school and made a promise. A promise to meet again after exactly 3 years from that day. And the day of promise has finally arrived.

Two neighboring childhood friends. An airheaded girl and the boy who takes care of her like a mother hen. And of course, there is his family background with a tiny, insignificant supernatural secret. Now that her parents have left the girl in their neighbor's care, will she ever discover her friend's secret?