AI: The Somnium Files Wiki
AI: The Somnium Files Wiki

Day 5: Tuesday -seisAI- (5日目:火曜日 "制裁", 5-Nichi-me: Kayōbi -seisAI-, lit. Day 5: Tuesday -Punishment-) is a chapter featured in AI: THE SOMNIUM FILES.

It is the twelfth chapter featured in the Mizuki Route. It covers Kaname Date's continued investigation of the New Cyclops Serial Killings and his confrontation of a suspect.

Case File Synopsis

When he woke up, Date was lying on his sofa at home, with Mizuki beside him. Date got up to continue the investigation, but Mizuki demanded that she be taken along.

Date discovered that the bloodstain at the warehouse contained more than one person's blood. Just after that discovery, Date witnessed So dragging his left leg. Date collected the cigarette butt from the Kumakura office, and just as he suspected, the DNA matched the bloodstain. But then, the investigation was hastily shut down, and Date was sent a threatening video of Mizuki being held hostage. Date charged into So's mansion to rescue Mizuki. So was killed, and Date ended up with a bullet to the left eye...

Story Summary

Mizuki at home.

Home, Tuesday 8:02 AM

Date woke up at home, where Mizuki told him that Boss and Pewter dropped him off after the previous day's Psync. Mizuki had taken the day off for mourning, and asked Date to take her along on his investigation. After some convincing from Aiba, Date agreed.

Bloom Park, Tuesday - Free Move

Mizuki riding the merry-go-round.

Mizuki talked about her memories of riding the merry-go-round with her parents. It was one of the only times she felt her whole family had been happy together. After the park closed, Mizuki did not want to return, for fear of replacing her happy memories there with something else.

Date and Mizuki at the merry-go-round.

After a while, Mizuki asked Date about his definition of family. Mizuki explained that to her, family meant having an ordinary, caring relationship, something she was never able to have with her parents. Mizuki blamed herself for her parents getting divorced and later killed, causing Date to recall conversations he had with Shoko and Renju before he took Mizuki in.

Marble - Flashback

Shoko complaining to Date.

At Marble, over four years prior, Shoko complained about parenting Mizuki, and revealed that she would hit Mizuki for not listening to her. Date scolded her for abusing her child, and decided to talk to Renju about Mizuki's situation.

Renju drinking with Date.

Renju told Date that Shoko refused counseling, and he was unsure of how Mizuki could be separated from Shoko. He was also unwilling to take care of Mizuki himself, as he was busy running Lemniscate. After learning about the abuse, Date decided to start taking care of Mizuki.

Ikume Shrine, Tuesday - Free Move

Date praying at the shrine.

Date visited the shrine to take some time to think about the case. Together, he and Mizuki reminisced about her martial arts training. Before leaving, they prayed at the shrine.

Cold Storage Warehouse, Tuesday - Free Move

Best buds Mizuki and Kagami.

Inside the warehouse, Date remembered the wound in the polar bear's leg. Aiba analyzed the bloodstain on the floor to discover two different blood types were present. Date asked the inspector at the scene to analyze the bloodstain to find the culprit's DNA.

Lemniscate Office, Tuesday - Free Move

Receptionist waiting to be swooped to Atami...

Date asked the receptionist if she had seen anyone with an injured left leg, but she had no useful information. Mizuki asked inside the office as well, to no avail.

Sunfish Pocket, Tuesday - Free Move

Mizuki investigating Sunfish Pocket.

Date and Mizuki were unable to find any relevant clues at Sunfish Pocket.

Central Hospital, Tuesday - Free Move

Date and Mizuki visiting Ota.

Mayumi left Ota's hospital room when Date and Mizuki arrived. Mizuki praised Ota for his rescue of Iris, and he mentioned that Iris had not yet woken up. Ota was unable to provide any new information about the case.

Marble, Tuesday - Free Move

Mizuki at Marble.

Mama told Date that she had not seen anyone with an injured left leg, and did not have any additional information about the New Cyclops Serial Killings.

Driving, Tuesday

Driving towards ABIS.

Boss called Date and asked him to bring Mizuki to ABIS for an official questioning. Mizuki wanted to keep investigating, but Date had no choice but to bring her in.

ABIS HQ, Boss's Office, Tuesday 3:57 PM

Mizuki angry that she needs to stay behind.

Date dropped Mizuki off with Boss for her questioning. Boss let Date know that the blood analysis results were ready at the warehouse.

Harbor Warehouse District, Tuesday 4:43 PM

So Sejima escaping by car.

Date met with Kagami, who confirmed that the blood of two different people was found in the bloodstain at the warehouse. One was Ota Matsushita, but the other belonged to someone who was not in the police database. Aiba identified someone standing in the distance: So Sejima, who limped towards his car and drove away. Date concluded he must be the New Cyclops Killer because of his injured left leg, but Aiba explained that there was not enough evidence to bring him in. Date determined that his DNA could be found on the cigarette So was smoking in the Kumakura Office, and headed there to collect it.

Kumakura Office, Tuesday 5:34 PM

Date visiting the Kumakuras.

The ashtray had been emptied. When Date explained he needed the cigarette butts for his investigation, Moma was willing to assist, and had the cigarette butts brought from the trash. Date remembered the brand So smoked, identified the correct cigarette, and brought it to ABIS to be analyzed.

ABIS HQ, Tuesday

Boss's Office, Tuesday 6:45 PM

Presenting Pewter with DNA evidence.

Boss gave Pewter three hours to analyze the DNA left on the cigarette butt, and told Date that Mizuki had been taken home after her questioning. Boss mentioned that she hoped investigating So would not cause any trouble.

Psync Control Room, Tuesday 9:26 PM

Boss stopping Date from going after So.

Pewter returned with the DNA results: it matched the bloodstain from the warehouse. Date left to arrest So, but on his way out, Boss stopped him. She explained that So had connections to the higher-ups in the police department, and could not let Date go after him on their orders. After Date refused, Boss had no choice but to take him off the case.

Driving, Tuesday

Video of Mizuki restrained.

Ignoring orders, Date began driving to the Sejima residence. On the way, he received a video message that showed Mizuki being held hostage in his apartment. Date changed course to rescue Mizuki.

Home, Tuesday 10:08 PM

Date finding Mizuki.

Date eventually found Mizuki inside one of the large speakers of his sound system. He freed her from the speaker, and found a note on her back warning him to stop his investigation. After Mizuki had recovered, she told him that three men wearing masks had incapacitated her. Date told Mizuki he had identified the person in the polar bear costume, and the two set off for the Sejima residence together.

Sejima Residence, Tuesday 11:10 PM

Date infiltrating the Sejima Residence.

Date and Mizuki were met by a large force of bodyguards that refused to let them through. Mizuki used her pipe to knock out a number of guards, while Aiba assisted Date in leading them to the pond and knocking them all out at once by redirecting a bolt of lightning.

So holding Mizuki hostage.

During the fight, however, Mizuki was taken hostage by So and sprayed with tear gas. Date rushed into the mansion to rescue her, but So warned Date not to move any closer, or he would kill Mizuki. Date used Aiba's x-ray vision to identify where he was hiding, and, with Aiba's help, used Mizuki's iron pipe to redirect a bullet to hit So in the side. So collapsed, allowing Mizuki to escape, but as she ran to Date, So fired his gun at her. Date quickly shielded Mizuki and pushed them both out of the way, narrowly dodging the bullet. So shot at them a second time, and the bullet hit Date's left eye, knocking him unconscious and causing Aiba to shatter.

Mizuki holding Date, unconscious.

As Mizuki cried over Date, So stated that Date had been killed by his own father. He then turned to shoot Mizuki, but before he could, Date regained consciousness and shot So in the head, then passed out. Mizuki was left by herself, begging for Date to wake up.



  • The name seisAI (制裁) translates to "Punishment," which is seemingly referencing many things:


  • During the Free Time investigation segment at Bloom Park, when the second Marble flashback begins, Renju Okiura and Kaname Date are seen talking to each other over 4 years prior to the start of the game, before Renju and Shoko Nadami got divorced. However, Renju's model mistakenly contains Renju's watch on his left wrist, as the watch is an anniversary gift given to Renju by his new lover after the divorce.
Full AI: THE SOMNIUM FILES spoilers beyond this chapter here!
  • All appearances of So Sejima in this chapter are actually of Saito Sejima, as a parasite in his own father's body. This can be noted from various facial portraits exclusive to this chapter labeled as "Saito" in the files, mocking allusions to "killed by your own father" when facing Date within his own body, and remarking to Mizuki if she likes fireworks, a recurring obsession used for Saito both in the game and in the Lemniscate series. Meanwhile, in Japanese:
    • Saito's quote about "killed by your own father" lacks a clear subject, which allows for a double meaning to his phrase, in which Saito is referring to So's body killing Saito's body rather than Saito killing Date.
    • When selecting to shoot at Saito, the text in Japanese specifies "Shoot Sejima," rather than "Shoot So," which is —potentially intentional— completely accurate as Sejima could be used to refer to either So or Saito.
    • Saito calls Date by the nickname "Date-kun" during this chapter, which Saito uses in other chapters but So never uses in any interaction with Date elsewhere.

References to Media and Pop Culture

  • During the Free Time investigation segment at Marble, if you examine the "Poster" on the wall, it will read "Twelve Angry Bullets." This is most likely a parody of the 1954 teleplay Twelve Angry Men, which was later adapted into two movies of the same name in 1957 and 1997.[1]


Kaname DateAibaIris Sagan/A-setOta MatsushitaMizuki OkiuraBossPewterNew Cyclops Killer
Hitomi SaganMayumi MatsushitaRenju OkiuraMamaShoko NadamiSo SejimaMoma KumakuraRohan KumakuraCyclops Serial Killer
#89FalcoBodyguardsTakero MatsushitaManaka IwaiSaito SejimaYakuza AYakuza BNurseReceptionistMermaidTaxi DriverInspector
Chiyoda District: Police Headquarters (Boss's Office; Psync Room; Interrogation Room) • Sunfish Pocket
Koto District: Harbor Warehouse District (Cold Storage Warehouse) • Date Residence
Meguro District: Sagan ResidenceTiefblau
Minato District: Sejima ResidenceKumakura OfficeIkume ShrineLemniscateCentral Hospital
Near Kabasaki District: Bloom ParkOld Chemical PlantMatsushita Diner
Shinjuku District: Golden Yokocho (Marble)
Other: Fuchu City (Fuchu Prison) • Akikawa ValleyOkutama MountainsEitoku High
SINKIN' IN THE BRaiN (Spoiler) • PSYNCIN' IN THE PaiN (Spoiler)
PSYNCIN' IN THE VaiN (Spoiler) • PSYNCIN' IN THE SWaiN (Spoiler)
PSYNCIN' IN THE VILLaiN (Spoiler) • PSYNCIN' IN THE MaiN: 1 (Spoiler)
PSYNCIN' IN THE MaiN: 2 (Spoiler)
Red Route: sigAIsaikAImeikAIsyokubAIrihAI
Yellow Route: syougAIseisAIhiAIsanpAI
Green Route: gumAIjukkAIkikAIjinnAIihAI
Purple Route: keitAIgyoukAIkyuusAIsyuurAIirAIdakkAIkekkAI
Pink Route: kenzAIjutAIkokkAIsousAIhakAIkassAI
Tokyo Metropolitan Police Department (Advanced Brain Investigation Squad) • Ujisaki Family (Kumakura FamilyKumakura Estates) • Secret Society NAIXATLOZForeign Mercenaries
LemniscateSunfish PocketMarbleTiefblauFamiSto8-12Elgorg
Wadjet SystemEvolverLight Synaptic Nerve Connection DeviceDate's CarShovelForgeOdoroki-man ChocolateGeostationary Satellite X00639
Chemical Plant ExplosionOriginal Cyclops Serial KillingsBreak-In at Sagan ResidenceNew Cyclops Serial KillingsIncident at Minato District HighwayDisappearance of Renju OkiuraOperation: Iris Rescue
Full List of Events


  1. Wikipedia page for Twelve Angry Men