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

"I have to find her. She's more important than any of you understand. But you'll see! You'll hear her music, just like I did! Then you'll see!"

—Ota Matsushita, on To-Witter

Ota Matsushita (真津下 応太, Matsushita Outa), known online as Mato and tAotemAs, is a major character in the Lemniscate YouTube series. On To-Witter, his account is Mato @Ota_Matsushita, and on Discord, his account is @tAotemAs#3395.

Ota is a 24-year-old NEET and a Net Idol otaku, specifically an enthusiastic follower of A-set who hopes to one day be a successful light novel author. He often comes across as cowardly and antisocial, and has an unrequited crush on Tesa. Under the pen name Odoin Kyoma[1], he's currently writing the novels Love Songs From Another World and Virtuoso of the Space Time Continuum.

In the Lemniscate YouTube series, he's very active on To-Witter, frequently interacting with Tesa, and even appearing in a few of her videos. In March, he became aware of Tesa's strange disappearance, and independently investigated the incident with the help of his followers.


Ota is a 23-year-old (now 24) otaku NEET who appears much younger and smaller than his actual age. He has brown hair, which is smooth bangs on the front but spiky from the back, with the majority of his hair covered by his red cap, and his eyes are a pale brown.

He wears a long-sleeved light-blue hooded sweater with the word GEEK on the front. Over this, he wears a grey zippered coat with a white star inscribed in a red and blue circle below each shoulder. He wears a red cap with goggles strapped above the bill. He carries a black backpack and wears a Rider Belt based around Kamen Rider.




Early Life[]

This section is a stub. Expansion needed.

Ota was born to Mayumi Matsushita and Takeo Matsushita around 1995. He has lived at the Matsushita Diner for his whole life. As he got older, he gained an interest in animated series, video games, and sentai shows. At some point, he began working on a light novel story of his own, but whether it is officially published or a doujin is unknown.

Befriending Iris, Mizuki, and Amame[]

This section is a stub. Expansion needed.

Some time in the past, Ota met Iris Sagan and Mizuki, and as their friendships grew, he began to grow feelings for Iris. Ota and Iris spent a lot of time hanging out together, either shopping or at each other's houses. Once Iris started her net idol career as A-set and her videos on her Lemniscate channel, Ota was one of her biggest supporters.

A-set's Career[]

This section is a stub. Expansion needed.

Ota wrote a long and heartfelt poem addressed to A-set, which he sent as a response to her over To-Witter for Valentine's Day. He was subsequently ridiculed by the responses of other To-Witter users. A-set invited Ota to help film her Valentine's Day themed video at Sunfish Pocket, titled "Tesa Visits Maid Cafe Sunfish Pocket!" There, she read his poem out loud to her entire audience. At the end she commented, "This is creepy!" and proceeded to dismiss any romantic advances from Ota, much to his dismay. Ota ultimately spent his Valentine's Day alone watching anime at home, although he at least received a new-found meme from Iris based on his appearance on her video.

Over the following weekend, Ota attempted to find ways to meet up with Iris, such as via online multiplayer in a video game. On one of her tweets about urban exploration, Ota offered to go with her to help film an urban exploration video, but she went alone to record her video for the following day. Worried about her, Ota attempted and failed to contact her while she was exploring, which made him nervous about her whereabouts. Once the video was released, a distortion in the video containing an ominous message prompted Ota to confirm Iris's safety.

The next day, Ota and Iris went on a trip to Akihabara to relax after the events of the previous day. Over the weekend, he spent some time working on his light novel series. The next week, Iris and Mizuki visited Ota at his home. Ota and Mizuki left to buy snacks while Iris filmed her next video at the diner. Another distortion in the uploaded video caused Ota and Iris to worry even more, and Ota rushed to Iris's house to confirm her safety. While consoling her, Ota concluded that the distortions were a prank orchestrated by A-set's haters and were overall harmless.

For the next few days, Ota tried and failed to get lunch with Iris and Mizuki and spent time debating online with people about what he considered accusations and conspiracy theories about his relationship with Iris. During this time, Ota commissioned the To-Witter user @fluerichaji to draw art of A-set wearing a Sunfish Pocket mer-maid uniform, which he eventually uploaded as his profile banner. When more distortions were found in A-set's next video, Ota attempted and failed to help decode them. A few days later, on International Women's Day, Ota spent all night long playing Nier:Automata, waking up late the next morning as a result. Eventually he helped Iris back up all of her videos in order to prevent any more interference from outside sources. On the day Iris was set to fly to San Francisco, he discussed sexiest female character themes on To-Witter.

Iris's Disappearance[]

This section is a stub. Expansion needed.

The day after Iris left for San Francisco, a strange video was uploaded to A-set's channel, titled 6, in which her empty home was filmed by a different camera than her usual videos are recorded in. Extremely worried about this strange upload, Ota attempted to make contact with Iris via phone, To-Witter, and NILE, but he failed to contact her. Ota began looking for information about what happened to Iris. He learned from Hitomi Sagan that Iris left for the airport, but later learned from the airline and the staff at the hotel that she did not arrive for her flight or at her hotel. Worried that Iris may have gone missing, he began to dig deeper. He determined that Iris was still in Tokyo.

Using wifi towers, Ota was able to determine that Iris's cell phone was connected somewhere near the water, presumably around Ariake, and he found an encoded message that read CRAMER DIAVOLO. When he reported this on To-Witter, several followers came to the conclusion that this phrase was connected to Lemniscate. After continuing his search, Ota realized that the phrase CRAMER DIAVOLO was always accompanied by a string of code: "59112518581132 57181510291 421513 5281589196 1811291151". When inquiring online again, one of his followers, @maxigregrze, deciphered the code as "Okiura Fishery Cold Storage Warehouse," which Ota recognized as a building in the Harbor Warehouse District. He almost went to search the building, but his followers convinced him not to go in rashly.

After a direct plea from Kotaro Uchikoshi to find Iris after a week of inactivity, Ota decided to search the warehouse. He live-tweeted his findings as he explored. He found an operating table and a saw blade above it with no sign of Iris anywhere. Unable to locate her, Ota began to panic on his To-Witter just as a new video was uploaded to the Lemniscate channel, showing footage of Iris being murdered by a person in a polar bear outfit.

The Impostor[]


A-set's Return to YouTube[]


A-set's Hiatus[]



Lemniscate YouTube Series
Uchikoshi Introduces Net Idol A-set! Tesa's Top 3 Favorite Snacks and Mascots! Tesa Visits Maid Cafe Sunfish Pocket! There's No Way This Trespassing Idol Can Be This Cute! Tesa's Matsushita Diner Review! Omelet Rice Edition! A-set Reservations Unknown
Absent Absent Appears Absent Appears Absent
6 rw nw prt m hrw A-set's GDC All-Access Convention Report! Sneaking Into ABIS! Exploring a Dreamworld! This Is Your Idol
Absent Absent Absent Absent Absent Absent
Zanki Zero Let's Play! Can Tesa Survive the Ruins?! It’s time to talk about the Cyclops Case (might lose subscribers for this...) My 10-Day Vacation Diary AI: THE SOMNIUM FILES Let's Play! Detective Tesa! That Time I Got Forced To Do Impressions by an Egyptian God Tesa's Spirited Away Adventure: Picture Book Edition!
Absent Absent Absent Mentioned Mentioned Mentioned
Tesa Answers Over 30 Questions at Super Speed! "Invincible Rainbow Arrow" Dance feat. Mizuki, Ota, and...White Horse Woman?! Sneak Peek at AI: THE SOMNIUM FILES LE/Day One Edition! You Won't Believe the Friend I Just Made! Graduation A-set's AI: THE SOMNIUM FILES Exclusive Launch Day Let's Play
Mentioned Appears Mentioned Mentioned Absent Absent
AI: THE SOMNIUM FILES Let's Play Part 2! Ota is here!!!



  • Ota's online nickname, Mato, could have been made similar to A-set's fan name, Tesa, which is simply "A-set" in reverse. In lieu of this, Mato is likely a reverse of Ota Matsushita.


  • Ota was originally planned to be a completely disproportionate character compared to the rest of the cast in the game (much like certain characters in the Danganronpa series). While all character models would be made with human-accurate proportions, Ota was planned to be in a completely different style, standing at around waist-height and having an extremely large head. His beta design was a long-standing design that Yūsuke Kozaki had been waiting to use on a project, and decided to try out for Ota. However, the disproportionate plan for Ota was scrapped, as it would be difficult to model and would look too detached from the other characters in the game, and they were not confident it would look good.[3]
    • The team's opinion on the scrapped idea changed once the movie Spider-Man: Into The Spider-verse was released on March 8th, 2019. Seeing the various disproportionate Spider-folk appear next to each other in the movie in a way that looked great made the team realize that the idea was possible. However, by then the game was nearly done, with the Lemniscate video series already airing for over a month.[3]
  • Ota's Rider Belt appears to be based around the Kamen Rider transformation belts, specifically the Double Typhoon, worn by Kamen Rider V3 in the Kamen Rider series.
  • Ota's laptop has various stickers placed on its cover, a decent number of them being A-set memorabilia.[4] These stickers are the same ones to be included in the Special Agent Edition of AI: THE SOMNIUM FILES.[5]
  • Ota's Twitter account has contributed just as much, if not more, in world-building for the universe of AI: THE SOMNIUM FILES as A-set's account, revealing small information and details about the normal life in this world, as well as documenting the events of the story surrounding Iris's death.
  • According to an interview with Siliconera, Ota is Director Kotaro Uchikoshi's favorite character among the greyed out characters at the bottom of the cover art. Since Assistant Director Akira Okada answered Aiba, a character not included among the greyed-out characters, it was unclear on how specific Uchikoshi's answer was, until the Q&A panel at Anime Expo 2019, where he stated that, if he had to choose, his favorite overall character would be Kaname Date.[3]
    • However, he has stated numerous times that he loves all his characters, so any answer would potentially not be a true answer.
  • In a fan-made Character Poll for AI: THE SOMNIUM FILES held on Twitter, Ota Matsushita came in 14th place.
  • He appears to be a fan of:
    • The Danganronpa series[6]
    • Re:Zero — Starting Life in Another World[7]
    • Kill la Kill[7]
    • The Sword Art Online franchise, particularly Sword Art Online Alternative Gun Gale Online[7]
    • Oreimo[7]
    • Eromanga Sensei[7]
    • The DARLING in the FRANXX[7]
    • The Kamen Rider series[7]
    • Virtual YouTuber "Kizuna Ai"[7]
    • Virtual YouTuber "Nekomiya Hinata"[7]
    • Virtual YouTuber "Kaguya Luna"[7]
    • Virtual YouTuber "Mirai Akari"[7]
    • TRIGGER anime studio[7]
    • J-LIST online store[7]
    • FAKKU Hentai Publisher[7]
    • Vocaloid "Hatsune Miku"[7]
    • Ijiranaide, Nagatoro-san (TL: Please Don't Bully Me, Nagataro)[8]
    • The Pokemon franchise[9]
    • My Neighbor Totoro[10]
    • The Simpsons[11]
    • My Hero Academia[12]
    • NieR:Automata[13]
    • King of the Hill[14]
    • Fate/Grand Order[15]
    • Cowboy Bebop[16]
    • Kantai Collection[17]
    • Girls' Frontier[17]
    • Azur Lane[17]
    • TBA


Kaname DateAI-Ball/AibaIris 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
Lemniscate YouTube Series
Lemniscate (channel)To-Witter Archives 2019 (Tesa)To-Witter Archives 2020 (Tesa)

To-Witter Archives Aseton: Main PageAseton Plays DanganronpaRevisiting the YouTube seriesTokyo Game Show & AI Launch DayAseton Zero EscapeAseton Terraria PioneerCrypt of AsetonAseton of HyruleIndivisible Aseton
Weibo Archives
A-set To-Witter (English)A-set To-Witter (Japanese)a_set_on Weibo (Chinese)Mato To-WitterKotaro Uchikoshi Eng To-WitterFluerichaji To-Witter

Love Songs From Another WorldVirtuoso of the Space Time Continuum
A-set (impostor) • Ota MatsushitaMizukiKotaro UchikoshiFluerichajiWhite Horse WomanBloody Polar Bear
Renju OkiuraHitomi SaganMayumi MatsushitaMama****** ****AI-BallBossPewterYūsuke KozakiAkira OkadaCyclopsAmame DoiHorusBastet • "Uncle" • Missing Girl • Missing Girl's Parents
Tokyo: Sagan ResidenceLemniscate OfficeSunfish PocketKabasaki DistrictBloom Park (Somnium) • Old Chemical PlantMatsushita DinerIkume ShrineGolden Yokocho (Marble) • Harbor Warehouse District (Okiura Fishery Cold Storage Warehouse) • Sejima ResidencePolice Headquarters (Boss's Office/Psync Room) • Okutama Mountains
USA: San FranciscoCalifornia
LemniscateSpike ChunsoftSecret Society NAIXATLOZGame Developers ConferenceSunfish PocketMarbleTokyo Metropolitan Police Department (Advanced Brain Investigation Squad) • Anime Expo
A-set's video seriesCyclops Serial KillingsChemical Plant ExplosionDisappearance at Bloom ParkA-set's campaign against NAIXATLOZSpike Chunsoft's panel at GDC Disappearance of Iris SaganImpersonation of Iris SaganIris Sagan's playthrough of AI: THE SOMNIUM FILESVisit to the Somnium Files DiscordSpike Chunsoft's panel at Anime Expo 2019
Videos (Pre-release)
0: Uchikoshi Introduces Net Idol A-set! (Invincible Rainbow Arrow)
1: Tesa's Top 3 Favorite Snacks and Mascots!
2: Tesa Visits Maid Cafe Sunfish Pocket!
3: There's No Way This Trespassing Idol Can Be This Cute!
4: Tesa's Matsushita Diner Review! Omelet Rice Edition!
5: A-set Reservations Unknown
fAInal: rw nw prt m hrw
A-set's GDC All-Access Convention Report!
Sneaking Into ABIS!
Exploring a Dreamworld!
This Is Your Idol
7: Zanki Zero Let's Play! Can Tesa Survive the Ruins?! (Alt)
8: It’s time to talk about the Cyclops Case (might lose subscribers for this...)
9: My 10-Day Vacation Diary
10: AI: THE SOMNIUM FILES Let's Play! Detective Tesa!
11: That Time I Got Forced To Do Impressions by an Egyptian God
12: Tesa's Spirited Away Adventure: Picture Book Edition!
13: Tesa Answers Over 30 Questions at Super Speed!
14: "Invincible Rainbow Arrow" Dance feat. Mizuki, Ota, and...White Horse Woman?!
15: Sneak Peek at AI: THE SOMNIUM FILES LE/Day One Edition!
16: You Won't Believe the Friend I Just Made! (Secret video)
17: Graduation (AX Panel)
Videos (Post-release)
18: A-set's AI: THE SOMNIUM FILES Exclusive Launch Day Let's Play
19: AI: THE SOMNIUM FILES Let's Play Part 2! Ota is here!!!


  1. 1.0 1.1 Day 2: Saturday –saikAI
  2. Tweet from JP A-set
  3. 3.0 3.1 3.2 Spike Chunsoft's Anime Expo 2019 AI: THE SOMNIUM FILES panel
  4. Mato: "I think I should get more stickers for my laptop. I've already got it mostly covered in @Lemniscate_Aset stuff but...there's always room for more stickers. Thoughts?" (Mar 2nd)
  5. A-set video: "Sneak Peek at AI: THE SOMNIUM FILES LE/Day One Edition!"
  6. Mato (in reply to @bribriHEARTS): "tokomaru, saimatsu, chimondo" (Feb 22nd)
  7. 7.00 7.01 7.02 7.03 7.04 7.05 7.06 7.07 7.08 7.09 7.10 7.11 7.12 7.13 7.14 7.15 Mato's list of accounts he follows, which contain official accounts of many anime series and other pop-culture media.
  8. Mato: [two images included] (Feb 26th)
  9. Mato (in reply to A-set): "I like water types! And anything that looks like a ninja or a robot, lol" (Feb 27th)
  10. Mato (in reply to A-set): [gif included] (Mar 1st)
  11. Mato: "Everyone coming up with conspiracy theories like" [gif included with tweet] (Mar 1st)
  12. Mato: "Plus, you know I'd never let anything happen to my muse! My inspiration! My raison d'être! I'll protect her!" [gif included with tweet] (Mar 2nd)
  13. Mato: "Ugh, just woke up. Probably shouldn't have stayed up all night. But hey, if you want to Become as Gods..."(Mar 9th) ["Become as Gods" is a notable quote from the video game NieR:Automata]
  14. Mato (in reply to @maxigregrze): [gif included in tweet] (Mar 11th)
  15. Mato: "Those 'who would win in a fight' questions are boring. We get it already. The real important question is: Pirates vs. Ninjas vs. Knights vs. Samurai: who is SEXIER?" (Mar 12th), followed by Mato: "I mean I'm kinda leaning toward pirates because" [image included with tweet] (Mar 12th)
  16. Mato: "COWGIRLS I FORGOT ABOUT COWGIRLS" [gif included with tweet] (Mar 12th)
  17. 17.0 17.1 17.2 Mato: "You know what? What if we introduce planes and boats into the picture? Now who wins? lol" [images included in tweet] (Mar 12th)