Keiichi Maebara, a student who recently moved into the village of Hinamizawa, is invited by his new friends at school to join their club. But while searching for treasure at a garbage dump with Rena Ryugu, he discovers the village is not as peaceful as it seems.

Keiichi meets Mion's twin sister, Shion; the two are so identical that Keiichi can hardly tell the difference between them. It is also revealed that Mion has a crush on him.

Rena's madness reaches the peak to the point of taking all the school children hostage. With the police's help and working together with the rest of the group, Keiichi manages to defuse a homemade bomb Rena planted on the rooftop of the school. There, the two have a final confrontation and even though he is defeated, Keiichi manages to get Rena to realize she should have trusted and confided in her friends.

The day of the Watanagashi Festival comes, and once again Rika fails to warn Tomitake of his imminent death. Later, Satoko is convinced that a mysterious man is following her and Rika around, even though no one else has noticed any such thing. Worried of Rika's safety, she sets traps around the house to alert her of any intruders, and when one is triggered, her fears are confirmed.

The fight to save Satoko from her uncle's abuse continues, but they stumble on a dead end because she is reluctant to denounce him, for her own reasons. Rika realizes that despite their, she is the one who must take action.

A new OVA series to commemorate the series' 10th anniversary.