is a Japanese horror adventure game by Hoshikuzu KRNKRN (Makoto Sanada) for Microsoft Windows, PlayStation 4, Xbox One 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.

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 volumes and has over one 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 manga series was 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. A prequel titled was released as part of bonuses included in limited edition Blu-ray and DVD boxsets of the anime's first volume.

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 master. The two, now in the same situation, form an alliance where Zack can use her intelligence to escape, and upon doing so will fulfill Ray's desire to be killed by him.

Ray and Zack continue to go to the upper floors to find a way out, defeating the two other floor masters, Edward "Eddie" Mason at B4, a young boy with an unhealthy obsession with graves, and Catherine "Cathy" Ward at B3, a sadomasochistic former jail guard, in the process. When Zack gets injured during the fight against Cathy, Ray encounters a reverend, Abraham Gray, at B2 who reveals himself to be the one who designed the game in order to figure out the definition of "religious faith" in people's hearts, appointing the various floor masters as "angels" that are not afraid to kill without hesitation. Although Gray lets Ray return to B5 to get medicine, she must pass through a trial to determine her identity before she can proceed to the next floor. Meanwhile, back on B2, Zack discovers that Danny is still alive, the latter having faked his death. Ray is forced to confront her selfishness in the trial but survives through it to save Zack, convincing herself that he is her God.

When the duo arrives at B1 though, they come to a house filled with fake flowers and the stitched corpses of a couple, driving Ray hysterical and desperate for Zack to kill her immediately. Danny then tricks Zack into leaving Ray alone in the room and locking it up, forcing Zack to search the floor in order to discover the truth about Ray. With help from Gray, Zack discovers that Ray suffered in the midst of her parents' terrible relationship, and subsequently both were killed, with her father killing her mother, and Ray shooting her father. After this, she stitched their corpses together to form her new "perfect family". While counseling her at the hospital, Danny took an interest in her blank blue eyes and used his authority as an "angel" to bring her to B1, making her the final floor master. However, after discovering a bible, Ray suddenly found herself unable to cope with the realization and guilt of what she had done, believing that no one would accept her after what she did, so she developed suicidal ideations and erased her memory, causing Danny to send her to B7 with the hopes that she would return to her "original self". As Zack finds out the truth, Ray, coming to the realization that Zack won't become the God she desires, shoots Danny and attempts to kill Zack by leading him around the traps of her floor, but he helps her to come to terms with her actions and both renew their oath.

Just as they reach the exit, Danny activates the self-destruct sequence of the building and critically shoots Ray. However, before he can kill Ray and Zack, Gray, having completed his experiment, appears and kills Danny, allowing Zack and Ray to escape just as the building burns down. The police then promptly arrive and Zack lets himself be arrested to save Ray's life as paramedics took her away. After recovering, Ray is taken to a Rehabilitation Center due to her apparent delirium and attachment to Zack. An unspecified amount of time has passed, presumably weeks to a few months after the incident, Zack is sentenced to death.

One night, as Ray prepares to spend the night without sleeping, however, Zack somehow escaped prison and breach the Rehabilitation Center to pick up Ray. Realizing that Zack is still intent on keeping the promise between them, Ray once again implores Zack to kill her as they escape. By the time Ray's caretaker and the police break through the door, Ray and Zack have disappeared, leaving only Zack's knife behind beneath the windowsill.

Characters Main characters /

The 13-year-old female protagonist of the story. After witnessing a murder, she is taken to a hospital for counselling, only to wake up on Floor B7 with no memories from her past. She later recovers them after a scuffle with Danny, the doctor responsible for counselling her, and reverts to an apathetic character. Believing death will be her salvation, she requests Zack's help to kill her in exchange that he can use her intelligence to help him escape the building. Under her emotionless and calm exterior though, Ray harbours a morbid interest in stitching up animals or people she deems imperfect and a twisted perception and blind faith in God. Her interests stemmed from her parents, who hated each other. Ray then witnessed her father kill her mother, avoiding her by divorce and in terror, killed her own father with a gun, before deciding to stitch up their corpses to turn them into her "perfect" parents. Taken to the hospital, Danny develops an interest in her blank blue eyes and uses his authority to make her the floor master of B1. Ray's floor is modelled after her house and is filled with many deadly traps with the exception of her bedroom and living room where the stitched corpse of her parents is placed. /

The 20-year-old male protagonist of the story. Once an infamous serial killer, he is now the floor master of B6. He is noticeable for his body being completed covered in bandages and wields a grim-reaper-like scythe. Bloodthirsty, Zack delights in destroying the happiness of his victims and filling them with despair. As Ray showed a severe lack in emotions, he found no interest in killing her and let her stay alive for him to use her intelligence to escape the building, in return that he will kill her once they escape. Zack grew up only knowing how to kill due to being treated abusively as a child. Abandoned by his parents, but his stepfather tried to burn him and his mother was killed wounding his body with burns that he covered up with bandages and causing him to develop an intense fear of fire. His mother then left him in the care of an illegal orphanage that trafficked children, where he faced subsequently more abusive treatment, becoming a tool of labour; After his mother's death, his stepfather cheated on his mother, who abandoned him.Upon watching a slasher horror movie left by the head of the orphanage, Zack was inspired to go on a murder spree, with the heads of the orphanage being his first victims. He is subsequently found by Gray and became a floor master. His floor is modelled after a deserted, dirty network of alleyways.

Supporting characters /

A counsellor who has an insane obsession with eyes, especially Ray's blank, blue ones. Due to being born without a right eye, he was bullied for most of his childhood. His missing eye also caused fights between his parents until they divorced and his mother committed suicide. From there, Danny began to find blank, dead eyes like his mother's beautiful, becoming a counsellor to search for eyes that could satisfy him. Prior to the series, he was a counsellor for prisoners and met Gray, who offered him the chance to become the floor master of B5. Believing it could satisfy him, Danny took on the offer and subsequently used his authority to bring Ray into Gray's experiment and make her the floor master of B1, hoping that he could live close to her eyes. He is ultimately killed by Gray in his pursuit for Ray. In the prequel manga Episode.0, he becomes the main character. /

A young boy characterised by his pumpkin mask and love for making graves. His floor is modelled after a graveyard and made completely out of stone. Born a child of grave-makers, Eddie was proud and skilled at his job, but became discontent with the fact that he was never given anything that could truly belong to him, for most of his things were hand-me-downs passed from one child to the next. He then began to kill his pets and bury them in his own graves, feeling that things only truly belonged to him once they were put in graves dug by him. When he was invited by Grey and became the floor master of B4, he began building graves for those killed by the other floor masters, hardly ever killing anyone himself. However, he took it upon himself to kill Ray and bury her in a beautiful grave after falling in love with her at first sight. Due to constantly building graves in the dark, Eddie got used to seeing in a dark environment, which gives him the advantage when he kills. He is killed by Zack when Ray turns on the lights, and buried in the grave originally meant for her. In the game prequel Episode.Eddie, which focus more on his past before becoming floor master, he becomes the main character. /

The floor master of B3, who is known widely as the "Condemner" due to her past as a former jail guard, with Danny as her prisoners' counsellor. A sadomasochistic woman, Cathy delights in uncovering her criminals' crimes and delivering punishment to them through torture, often killing them. Those who survive are then confined as her playthings. She is the most formidable of all the floor masters due to her wide range of death traps and torture instruments. Viewing Zack as an exemplary sinner, she attempts to punish him thoroughly to her amusement but is killed when Ray catches her off guard with a gun. Her floor is modeled after a huge jail block, along with her private room where she controls the various traps on the rest of the floor and monitors her victims. /