Yasuhiko is a transfer student to a classroom with Miyuki. She barely notices him until he suddenly appears before her in the library. The truth comes out: Yasuhiko is from the future. Bound by this special secret, they become closer and closer. Yasuhiko reveals that this trip is inspired by a book from Miyuki’s era, a book, she later learns from her future self, that she authored. On the day of his departure, Miyuki makes a promise, that she will write that novel to treasure this unforgettable summer, just as her future self says. Ten years later, the book is about to be published. As Miyuki waits to reunite with her past self, nothing happens! Did something go wrong in the past? Are there more secrets to come?