Yousuke returned to his hometown of Oboshiro-mura after 8 years in Tokyo and Osaka. He had received a letter from Father Arakawa, who had raised him up as a child, telling him that the Oboshiro church will be closing and merged with a larger church in a neighbouring town, and inviting him back for one last summer together. He reunited with his childhood friends Yomi, Daiya and Ruka, and also met a little girl named Hina who reminded him of himself when he was a child. This is the beginning of a cheerful and refreshing, yet sometimes painful, summer tale.

An updated release titled Himawari no Kyoukai to Nagai Natsuyasumi -extra vacation- was released 7 months after the initial PC release. It includes new event CGs as well as a new route for Tsukiko.