The white-haired girl, Haine, appears in the sky as the ritual reaches its peak, and the island begins to be engulfed in shadow. A Desperate Last Stand
During the confrontation, a massive flash of light erupts at the shrine, effectively completing the ritual and killing nearly everyone present, including Sou and Mio. Summertime Render - Episode 12
The episode begins with revealing her complicity with the Shadows. She explains that her family has been feeding the dead to Haine (the "Mother" shadow) for generations. This gruesome tradition was maintained under the belief that as long as Haine lived, their own mother—who had been turned into a Shadow by their father to "save" her—would continue to exist. The white-haired girl, Haine, appears in the sky
In a final act of desperation, Shinpei decides to reset the loop. He asks Ryuunosuke (Hizuru's brother residing within her) to kill him so he can carry the information they've learned into the next cycle. She explains that her family has been feeding
The episode concludes with Shinpei’s death, triggering a new loop where he must find a way to prevent this massacre from happening again.
The powerful Four-Armed Shadow (Shide) appears, taking Mio hostage and overwhelming the group.
Haine, appearing in the form of a young girl named Shiori, is no longer satisfied with just the dead and has begun targeting the living to prepare for the upcoming festival ritual. The Massacre at the Shrine