The Half Body Serial Killings, also abbreviated as the HB Case are a set of events featured in AI: THE SOMNIUM FILES - nirvanA Initiative.
It is a set of murders originally perpetrated by a criminal known as Tearer, defined by its victims being perfectly cut in half vertically on a subatomic level. It started on February 10th, 2020, when the right half of Jin Furue was discovered, but the left half was never found. The following two murders ended with finding both halves of bodies in different places. Six years later, on February 10th, 2026, the left side of the first victim was seemingly found, completely fresh with no signs of decay, which led to reopening the case.
The murders were ended and the victims were avenged through the murder of Uru Somezuki.
People Involved[]
Killer[]
Victims[]
Investigators[]
- Tokyo Metropolitan Police Department
- Crime Scene Investigation team
- Mikoto Ushidera (lead detective)
- Araya Kagami (forensic investigator)
- Policeman
- Advanced Brain Investigation Squad
- Boss (squad leader)
- Kuruto Ryuki (lead investigator - 2020)
- Tama (assistant investigator - 2020)
- Mizuki Kuranushi (supporting investigator)
- Marco (assistant investigator - 2026)
- Mizuki Date (lead investigator - 2026)
- Aiba (assistant investigator)
- Pewter (engineer and support)
- Kaname Date (supporting investigator)
- Crime Scene Investigation team
Persons of Interest[]
- Others:
- Iris Sagan (eyewitness)
- Amame Doi (eyewitness)
- Shoma Enda (eyewitness)
- Moma Kumakura (eyewitness)
- Chinpei Wagai (eyewitness)
- Kizuna Chieda (kidnapping victim)
- Gen Ishiyagane (character witness)
- Tokiko Shigure (character witness)
- So Sejima (character witness)
- Mamoru Bodai (character witness)
- Riichi Chieda (character witness)
- Hanayo Nasu (character witness)
- Lien Twining (investigation assistant)
History[]
Past: Six Years Ago, Original Case[]
The first murder of the case began on February 9, 2020, a day before the case was officially opened. At the Horadori Institute of Genetics, the culprit, Uru Somezuki, was kept confined in an underground room where he was used as an organ donor for Jin Furue over the course of many years due to his matching genotype. Jin, remorseful over the fact that Uru was forced to undergo much pain for the sake of curing Jin's right-body tumor disease, approached Uru in his underground cell to formally apologize to him. However, Uru was infuriated and held an immense hatred for Jin, and in a sudden outburst of anger, punched Jin in the right side of the face, causing one of his teeth to fall out. The punch also caused the back of Jin's head to hit the hard floor and crack his skull, and the combined impact of both caused Jin to pass out and become unconscious. Uru, having recently learned of the Horadori Institute having a pair of slicers to bisect bodies at the subatomic level, activated the slicers. He then placed Jin under one of the slicers and used it on him, cutting his body in half and killing him.
Uru then proceeded to adopt the name Tearer, and donned a new outfit and iron mask, to conceal his identity as Uru Somezuki. He placed the left half of Jin's body on the stage of the rooftop amusement park at Misetan. He implanted a sign linking a QR code to a special AR video in Jin's right half, and used NILE text messaging to blackmail the director of Studio Dvaita, Chinpei Wagai, who needed money to take care of his kid, offering him huge sums of money by asking him to leave his studio doors unlocked an hour before a quiz show was scheduled to air on February 10, and to ensure no one goes near the studio during said hour. During this time, he placed Jin's body, kept upright due to the sign and rigor mortis, on one of the railings of the ceiling with the intent that it would eventually fall after rigor mortis fades, and also implanted thermite bombs inside the body as well as carbon nanocables connecting the body to several parts of the studio, including a light switch. During the quiz show that day, during the hour in which Iris Sagan, Mizuki Date, Boss, Kuruto Ryuki, Moma Kumakura, and Chinpei Wagai were participating, the rigor mortis in Jin's body faded, and his body fell: due to the carbon nanocables, his fall triggered the light switch to switch off, causing a fake blackout. After the lights were turned back on, the body was discovered, publicly seen by everyone, with the sign "Fray to Free" publicly broadcasting the QR video. Within hours of the body being discovered, the thermite bombs in his body exploded, causing Jin's right half to burn.
Kuruto Ryuki, one of the newest members of ABIS, was assigned as its lead investigator. The next day Uru, as Tearer, went after his next victim, Chikara Horadori, whom he also harbored intense hatred for due to Chikara being responsible for kidnapping him and using him as an organ donor for Jin. Uru knocked out Chikara at his lab at Horadori Institute, brought him underground and placed him on the slicer, and used it to bisect Chikara's body, killing him on the spot. He then pasted both halves of Chikara's halves unto walls: his right half was pasted to a chalkboard in Class 3-A of Sekiba High, while his left half was pasted to a stone monument at Yoyagi Park. Uru also prepared four balloons containing cards containing hints pointing towards Horadori Institute's underground, at various locations, in hopes of "playing" with investigators in what he considered a game, and luring them to the underground in hopes that he could kill them to eliminate the threat of them catching onto him and arresting him.
Meanwhile, as Ryuki was investigating leads for the case, he eventually managed to discover how the body was placed at the Studio, and how it fell and exploded. He approached Chinpei Wagai at Sunfish Pocket for information, and after dodging several shots from Chinpei, cornered him for information. The latter confessed about his conversation with Tearer, and revealed the NILE messages Tearer had sent him. Tearer then sends a message to Chinpei's phone telling him to go to Class 3-A at Sekiba High to obtain his money: knowing that this was a trap, Ryuki goes in his stead. That night, as Ryuki arrives, he immediately discovers the right half of Chikara's corpse.
The case would officially be dubbed the "Half-Body Serial Killings" by the police. The next morning a civilian discovered the left half of Chikara's corpse at Yoyagi Park while jogging and reported it to the police. Unbeknownst to Ryuki, Boss secretly appointed her adoptive daughter, Mizuki Kuranishi, who was also a secret member of ABIS, to serve as a supporting investigator as she considered Ryuki to be too unstable to be trusted to handle the case by himself. Mizuki arrived on the scene at Yoyagi Park that morning. She discovered Chikara's corpse, but through investigation also discovered a soda can and balloon egging investigators on into a game. While Ryuki is out on the case, Mizuki decides to play Tearer's "game", and manages to locate every balloon, barring one which she later discovers was popped and disposed of by Gen Ishiyagane. She approaches Gen at Brahman and interrogates him, then brings him to ABIS to Psync with him: she then learns what the final card had said. Putting the pieces together, she manages to piece together that the puzzle points to the Horadori Institute's underground. She brings along her old friend, Lien Twining, to help her get to the Horadori Institute's underground due to the latter's lockpicking skills and history working with Horadori Institute, and the two break into the Institute together, avoiding guards in the process, while discovering the underground of the institute. Before they can investigate, however, they realize that Tearer is approaching and escape before the latter can do anything to them.
Earlier the next morning, Andes Komeji, extremely drunk and badly in debt from borrowing money from loan sharks, discovers the left half of Jin Furue's corpse at the top of Misetan while trying to find his bowtie he obtained from his son, Shoma. He decided he wanted to blackmail Tearer for money, and grabbed Jin's corpse and placed it in his suitcase to use it as a weapon against Tearer. Later that day, he sobered up and realized his mistake, and out of fear, contacted his daughter, Amame Doi, and asked her to hide the corpse. While the latter was frustrated with her father for his recklessness, she nonetheless agreed, and asked Gen to hide Jin's left half in the freezer of Brahman. Gen agreed to do so, and he hid Jin's corpse, locked the freezer, then disposed of the key so that no one would be able to open the freezer. Upon realizing that Komeji had stolen Jin's left half, Uru became frustrated with Komeji as he considered the corpse vital to hinting towards the location of his ultimate plan, the Nirvana Initiative. Uru asked Komeji to come to Horadori Institute, and the latter arrived with a gun to defend himself. Ryuki catches Komeji and brings him to ABIS for interrogation. Through a Psync, Ryuki learns that Komeji had something Tearer considered important. Uru reaches out to Komeji via NILE and offers Komeji a chance to return Jin's body at Studio Dvaita, but Komeji instead arrives with Ryuki in hopes of ambushing Tearer. Realizing this, Uru prepares a QR video to trigger Ryuki into a mental blackout and kidnaps Komeji. He brings the latter to Horadori Institute, places him under the slicer, and cuts him in half, killing him. He then places the two halves of Komeji's body at the locations where Jin's halves originally were: his left half at the rooftop of Misetan, and his right half at Studio Dvaita. While he's preparing the latter, he runs into Amame Doi who had rushed into Studio Dvaita, and corners her, threatening her not to say anything about this encounter. A few hours later, Ryuki awakens, and Iris, Kizuna, and Shoma arrive at the studio as well. All of them along with Amame discover the right half of Komeji's body.
The next morning, Mizuki Kuranushi discovers the left half of Komeji's body at Misetan, and investigates the scene, eventually learning of Komeji's previous involvement with discovering Jin's corpse and his interactions with Tearer. That afternoon, Uru invites Ryuki to talk and blackmails him, threatening to delete Tama's data and initiating a self-destruct function in Tama should he disobey. He orders Ryuki to lead Kaname Date to the Kabasaki Chemical Plant, as he considered Date to be a threat to his plan. He later kidnaps Kizuna that night, ties her up at the underground cathedral beneath the Naix Japan Building, and takes custody of her phone, and goes to the Kabasaki Chemical Plant. This lures in Mizuki Kuranishi, as well as Ryuki and Date. Mizuki holds Tearer at gunpoint, but Ryuki arrives and under Uru's orders, shoots Mizuki with a taser, knocking her out. Ryuki quickly escapes the scene before Date arrives, while the latter shoots Uru with anesthetic bullets. Mizuki Kuranishi uses this chance to Psync with Uru for information using the Prototype Psync Machine which happened to be present at the Chemical Plant. There, Mizuki learns of Tearer's past, how he was held captive at the Horadori Institute, and how he was used as an organ donor for Jin. Uru quickly wakes up afterwards, having developed a resistance to anesthetic due to being administered with it many times over his several transplant surgeries. He is shot in the mask by Date, which reveals the left half of Uru's face. Uru threatens Date and Mizuki, telling them that they cannot tell anyone about what they had seen and heard that day, and that he would kill Mizuki Kuranushi if they ever did so. He revealed he had significant money and hired several assassins, noting that his assassins would be able to find out and locate her even if he were to die.
The next day, Uru heads to the Sejima Residence and confronts his biological father, former Congressman So Sejima, although the latter does not realize that Tearer is his illegitimate son. He tells So about his mistress whom he had a child with, and later reveals to So the location of the "execution chamber": the underground of Naix Japan. Iris bore witness to this, and once Ryuki realized this, he brought her to ABIS to learn about this location in hopes of locating Kizuna. Ryuki arrives at the Naix Japan underground, and later, Date arrives with Mizuki Date, Lien Twining, and Gen Ishiyagane as backup. The five of them manage to ward off several Naix members, and attempt to rescue Kizuna, but Uru enters the scene. He reveals that his victims were used for the Nirvana Initiative, and also used Kizuna as hostage to lure in Date. He threatens Ryuki to kill Date, under the threat that if he does not do so within ten seconds, he will detonate the nearby thermite bombs. Even so, Ryuki cannot bring himself to do so. As such, Tearer detonates the bombs, then leaves, but not before holding Date captive. He manages to hold Date captive for a day, but the latter managed to escape.
The case subsequently went cold for the next six years, as Uru would then spend the next six years planning the Nirvana Initiative by preparing a rocket at the central Stadium that would unleash a virus known as TC-PERGE, with the intention of infecting the entire population with it in hopes of having humanity reach "Moksha" and in his eyes, have humanity escape a false world.
Present: Case Re-Opening[]
On February 10, 2026, Uru, having developed a fixation with Amame Doi from their previous confrontation, invites her to the Horadori Institute, and brags to her about his plan. He also inadvertently reveals to her that he is in fact Tearer. Not realizing that Amame was the daughter of one of his victims, Andes Komeji, he caused the latter to snap and in a fit of rage out of desire for vengeance, Amame hits Uru in the back of the head with a wrench, knocking him out. She then places Uru under the slicer, waits for him to wake up, and uses the slicer on him to kill him instantly, wanting him to die the same gruesome death he gave to her father.
Unbeknownst to Amame, Tokiko Shigure witnessed her killing Uru, and for the sake of her personal plan to achieve Moksha, blackmails Amame to do her bidding by threatening to reveal what she did if she does not comply. She has Amame carry Uru's left half to the stadium, which Amame does using Shoma's Roboji to do so, while Tokiko takes Uru's right half and hides it in a ritual platform in the underground cathedral beneath Naix Japan.
Amame would then use a burner phone given by Tokiko to reach out to Mizuki Date via NILE, telling her to come to the stadium and hinting towards the Half-Body case. Mizuki Date would arrive at the stadium and discover Uru's left half. The police arrived on the scene, though all of them initially mistook Uru's left half for Jin Furue: further reinforcing this was the fact that the DNA was taken from organs from Jin's right half long ago, and as Jin's organs originally belonged to Uru, this led to a false match between the two halves despite them being discovered six years apart. The fact that the left half discovered at the stadium was alive until very recently further confused investigators. The case was officially re-opened.
Two days later, Tokiko reveals to Amame that she intends to use the slicer on herself, and orders Amame to take her right half to her office at Naix Japan, which she does so after Tokiko slices herself in half. Later that night, Tokiko's right half would be discovered by Ryuki, officially adding Tokiko to the case's death tally.
The next day, shortly past midnight, Mizuki Date breaks into Horadori Institute alongside Lien Twining. They discover the Institute's underground, and in turn discover the slicers as well as Tokiko's left half. This in turn reveals to ABIS how the victims of the Half-Body case were killed. They also discover the room Uru was held captive in as well as his diary.
The following night and next morning, Mizuki Kuranushi and Kaname Date, the latter having returned and regained his memories, discover Jin Furue's left half in Brahman's freezer, as well as Uru's right half in the underground Naix cathedral, in both cases using Lien's lockpicking skills. They also discovered the hidden file where Tokiko reveals Jin and Uru's backstories as well as their true appearances. Upon this, they had discovered Jin and Uru's true halves and attributed them to their true identities, thus closing the loopholes of the case. As Uru was confirmed deceased, this effectively apprehended the culprit of the Half-Body serial killings as Uru, being the culprit, was killed himself.
Ryuki had Psynced with Amame the day prior, and while Mizuki Date, Mizuki Kuranushi, and Kaname Date contemplate on possible leads for Uru's death, Ryuki points them to Amame for a lead. They bring Amame to ABIS for information, and learn the truth about Uru and Tokiko's deaths.
As the case was officially solved, and the culprit was effectively apprehended via death, the Half-Body Serial Killings case was officially brought to an end. Amame Doi faces punishment for killing Uru, however, her sentence is said to be light due to the public opinion favoring her as a hero due to killing a man who was effectively a serial killer and mass terrorist, effectively bringing said criminal to justice, albeit in a vigilante manner.
Ryuji Diverge: Case Solved[]
On February 11, 2020, after learning of a special Nil Number from six years later via Mizuki Date and Mizuki Kuranushi listening to a hologram provided by Tokiko, the Frayer travels back to this day and re-enters Ryuki's perspective. With the knowledge the Frayer had gained, the Frayer indirectly informs Ryuki about everything that had happened in a different timeline, in turn also revealing to Ryuki that Tearer was in fact Uru Somezuki, and that he lived underground at Horadori Institute. Shortly after Chikara's murder, Ryuki catches Uru at the Horadori Institute Underground in his cell and arrests him for the homicides of Jin and Chikara.
Uru is ultimately sent to trial and convicted for both murders. He is sentenced to life in prison, and six years later, he remains behind bars. The case is solved early in this timeline, while Uru officially faces legal punishment for his crimes.
Trivia[]
- The initials for the Half Body Serial Killings, HB, share the same initials with Hidden Bats, an alternate reality game made in promotion for AI: THE SOMNIUM FILES - nirvanA Initiative.