As the new school term begins at Wakamiya High, shy bookworm Machi Tsukahara feels out of place in her lively class. One day, she finds a mysterious note in a library book with the word "Sakurasaku" written on it.

Machi, following her mother’s advice, responds to the mysterious letter she found in a library book, leaving her reply inside the same book. Will the original sender discover her response?

Ippei suspects the book Amari requested doesn’t exist, prompting the film club to investigate her past through Mine, the newspaper club head. Meanwhile, Machi exchanges letters with the mysterious figure through library books.

The film club, still unable to find the elusive book, wishes for Amari to return to the stage. They create an original picture book with a new ending based on the jeweler's story she once read, hoping to convince her.