is a Japanese horror adventure game by Hoshikuzu KRNKRN (Makoto Sanada) for Microsoft Windows and Nintendo Switch. It was created using RPG Maker and was originally released as freeware via the Den Fami Nico Game Magazine website on August 14, 2015. It launched on Steam in Japanese, Chinese, Korean and English on December 19, 2016. A prequel titled is released as part of bonuses included in limited edition Blu-ray and DVD Box Set of the anime's first volume. Two manga adaptations, one based on the game and one on the prequel, written by Makoto Sanada and with art by Kudan Nazuka, began serialization in Media Factory's shōjo manga magazine Monthly Comic Gene in 2015 and Kadokawa Pixiv in 2016, respectively. The first manga has been collected in seven tankōbon volumes and has over 1 million volumes in print while the prequel has been collected in two volumes. Following the adaptations, a 4-koma manga series titled Satsuten! and the three-volume novel series are published with art by negiyan and written by Kina Chiren. The series is licensed in North America by Yen Press, who published the first volume on November 14, 2017. A 16-episode anime television series adaptation by J.C.Staff began airing from July 6, 2018. Plot 13-year-old Rachel "Ray" Gardner is taken to a hospital for counseling after witnessing murder. However she wakes up to find herself on the basement Floor B7 instead with no memories apart from her name and the reason she came to the hospital. A series of mysterious broadcasts and scribbled messages on the wall set the scene as a game where each participant is designated a floor of their own, and anyone who trespasses on another participant's floor has the chance to be killed. Ray, ignorant of the details, is almost killed by serial killer Isaac "Zack" Foster, the owner of Floor B6, and captured by Daniel "Danny" Dickens, the owner of Floor B5 and the doctor who examined her. Danny, who has a maniacal obsession with eyes, desires Rachel's blue, once-blank eyes. During this time, Ray recovers her memory during the night when the murder occurred, just as Zack kills Danny for her, but spares Ray after losing interest in her lack of emotions. As Zack has killed someone that was not on his floor, the broadcast designates him as a "sacrifice" along with Ray, where they can freely be killed by any floor