Very soon Iokawa Karada will become a junior high student, and both of her parents have since passed away. She and her older brother, Hiro, live together. Although their days pass quietly, she gets the feeling that as her only blood relative, Hiro-oniisan has all the responsibility and she wants to quickly become an adult.
On the other hand, Hiro’s ex-girlfriend, Nogami Shoko cannot forget her feelings about Hiro, and is obsessed with escaping to old memories. So one day, Shoko’s adult body transforms into that of a child!
Karada uses a wishstone and says, "Please change my body.." The protagonists Karada and Shoko, and the people who surround, them are depicted in this summer fantasy.
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* thanks to Rinji-chan for description