At the Cotton Drifting Festival, Shion convinces Keiichi to sneak into a sacred storehouse with Miyo and Jirou. They ask him to keep it a secret, because if anyone finds out, all four of them will most likely be killed or sacrificed as part of the village's ritual.

"In the twenty years since the Hinamizawa disaster, the small village has become a literal ghost town. Terrible rumors about the mysterious gas leak that claimed hundreds of lives have kept even the most curious at bay. But on this night, fate has led five strangers to the abandoned mountain hamlet--among them a certain Mion Sonozake. As the footsteps of the living echo through the abandoned halls of Furude shrine, the sleeping demons of Hinamizawa...

When her grandmother's beliefs in Oyashiro-sama, a village god, take a frightening turn after a gas explosion destroys the villagers of Hinamizawa, Natsumi and her family wonder if they should have taken her seriously.

"You've already met Keiichi Maebara and his mischievous friends in the Abducted by Demons Arc. But Oyashiro-sama's curse is poised to strike anew in Hinamizawa village. When Keiichi spots tomboy Mion working at a maid café, he can hardly believe his eyes! But it's not Mion after all-- it's her identical twin sister, Shion. Keiichi's never heard of this 'twin sister' before and suspects it's just another one of Mion's pranks. But through Shion, Keiichi...

Based on the evidence detailed in Takano's notebook, Rena believes she's uncovered the truth behind Oyashiro-sama's curse and the mysterious deaths in Hinamizawa! But though Rena's theory fits perfectly with Hinamizawa's dark history, it is difficult for Keiichi to believe such an outlandish tale, especially given Takano's fascination with the occult. However, Rena cannot be diverted from her obsession with the plot she believes will inevitably destroy...

"Rena has taken extreme measures to protect her and her father's happiness, but such drastic actions have terrible consequences. When her friends learn of her crimes, they feel no revulsion toward Rena, but rather a sense of regret that they hadn't been able to help her and avert this tragedy. But even if they had sensed Rena's desperation, would her classmates' pity have transformed itself from sentiment into action? Hadn't they had the same opportunity...