Based on the erotic game by LiLiM.

A father lives with his two beloved daughters. A traveler came before them and said, "It comes when snow falls in summer. The destruction of the world, you can still stop it." With a thunderclap, calamity springs forth from the bottom of the earth. A voice from beyond the walls calls to the disaster stricken people. "The fruits are to be our slaves. That is Law." The traveler brandishes a sword. The father shields the daughters behind his back. Three fruits to be protected. The time will come when choices are to be made. Whatever shape it may take. The world will change. It must change. On the fate of those looked after.

Kou, the protagonist, belongs to a family in charge of a derelict shrine. Along with his childhood friends Azusa and Yurina, who lives next door, and his best friend Souma, they live a life of little worries. When summer vacation is nearing, Miu, a female transfer student arrived in Kou's class. That night Kou saw Miu wandering around holding a long object, and he asks her about it. "I'm looking for something. A very old book. It's something that's... in this town." That book has long been kept in the shrine of Kou's family, the Oosakaki. With that in hand, thunderbolt strikes, and the 'law' of the world is set in motion.

(Source: VNDB)