While searching for a stray ball sent flying at a Little Busters practice, Riki encounters Mio, a girl who always sits and reads in the shade of a tree with a parasol open. There's one book she's particularly fond of, but she won't tell Riki what it's about. When she loses the book, it's up to Riki to help her find it.

Mio has been absent from school for several days, and everyone, even the Little Busters, seems to be gradually forgetting about her. Riki finally spots her in the courtyard again, but he notices an unfamiliar loneliness in her eyes...

Kyousuke predictions of the final Little Buster member shocks Riki, but that is not the bombshell that will be presented to Riki.