Throughout life, people come and go, eventually departing with a goodbye. For childhood friends Natsumi Aizawa, Yuka Hanaki, and Rinko Tamaki, they are confronted with this harsh reality when they are told their group's fourth member, Saki Mizukoshi, is moving away at the end of summer. With this news threatening their friendship, the four girls seek out a magic stone from local folklore—hoping to use its rumored wish-granting powers to keep them together. After following the steps of the supposed legend, they are surprised to discover that the magic is real. While the summer's end looms over the horizon, Natsumi and the others use the stone to ensure they have no lingering regrets until the end. But regardless of what the future might bring, these four friends will never forget the color