Orphaned siblings Kokoro Suzuhara and his blind sister Yume are whisked away to Hoozuki Island, a secluded place housing both their residence and school. Expecting tranquility, they instead encounter a group of wary children who suspect their teachers harbor dark intentions. As Kokoro delves deeper, he unravels shocking truths, aligning with his peers to break free from the ominous grip that ensnares them. Driven by a desire to protect Yume, Kokoro unknowingly sets off a chain of events with dire consequences for everyone involved.