AI: The Somnium Files Wiki
AI: The Somnium Files Wiki
For other uses of the term A-set, see A-set (disambiguation)


"Good evening, good morning, and hello! It's the brand-new star of the net world, Tesa, also known as A-set, you bet!"
—Iris Sagan's video introductions, as A-set

Iris Sagan (左岸 イリス, Sagan Irisu), professionally known as A-set, and fan-denoted as Tesa in English and Aseton (あせとん) in Japanese, is an online Virtual YouTuber and the protagonist of the Lemniscate video series. On Twitter/To-Witter, her accounts are @Lemniscate_Aset (in the English continuity) and @a_set_on (in the Japanese continuity). In the Japanese continuity, she also obtained the Weibo account* named ☀a_set_on. She also has the Discord account @Lemniscate_Aset#5257.

She is a High School Idol, Let's Player, and Songwriter working under the media office Lemniscate. She creates content with the aid of her producer Renju Okiura, the president of Lemniscate. She wrote the lyrics to her debut song "Invincible Rainbow Arrow".

In truth, there are two separate Iris within the story of the video series, unofficially denoted as Prime Iris and Alpha Iris. Prime Iris produced her video series from January until March 2019, leading up to her disappearance and apparent death at the end of March. Alpha Iris produced her series from January to July 2019, with an inexplicable gap in time during March and April. 


Iris artwork.png

Iris is a 17 year old high school girl (presently 18 year old)[3], officially measuring around 157 cm tall.[2] She has short pink hair split into two short pigtails ending below her shoulders, and her eyes are light blue.

Her outfit consists of a long sleeve shirt, two layered jackets, a fanny pack, blue socks on pink heels, and a cat-ear headset. Her t-shirt is white with long blue sleeves. Her button-up sweater is blue with long sleeves that end in fingerless gloves. Her letterman-style jacket is pink and white and features the "A" of her A-set logo on the back and the left breast side. Her fanny pack is cat-themed and is named after Bastet, an Egyptian goddess typically depicted as a cat. It is features a yellow and blue cat face, and the bag portion sits on her back. Her headset is black and white and features two cat ears.


Iris is a bright and cheerful young woman whose energetic optimism perseveres throughout all the content she produces, from her online videos to her To-Witter account. Her determination pushes her to train and do dance practice on various days of the week. Despite this up-beat personality, she often talks about murder or creepy urban legends, and seems to love them just as much as Boba Milk Tea. She is also capable of blackmail, so it is possible that she is actually cunning, despite how she might come off.

According to her official bio, her main interests were video games, movies, and the occult. Her favorite flower is the iris flower, presumably the type of flower she was named after. She places her interest in/talent of singing and dancing to her Net Idol work, and it is also said that she can run extremely fast. She has also been open on To-Witter about her enjoyment of food, in particular trashy food and snacks, such as pizza and chocolate.

Story (Tesa)[]


Iris's history in the ARG is the exact same as her history from the game. For a full bio on her backstory, see the main page.

Iris was born on October 26th, 2001, growing up with her single mother, Hitomi Sagan. Iris had a passion for dancing since she was young, and when she was around 12 years old, she had the dream to become an idol. Her mother's boyfriend at the time, whom she affectionally called "Uncle", encouraged her to take up a future in performance, and recommended the stage name "A-set" to use. In her teenage years, Iris took a part-time job at the maid cafe Sunfish Pocket, owned by a friend of her mother, named Renju Okiura, where she befriended Amame Doi, which lasted one year. After that, she began uploading videos of herself dancing and singing online, garnering the attention of a small fanbase, including the fan Ota Matsushita, along with various talent agencies. Worried about not knowing which agencies to trust, Iris and Hitomi reached out to Renju, whose also a talent producer, for advice, but he decided to take her into his talent company Lemniscate as the brand new talent. She began preparing for her career as an idol, where she befriended her fan Ota along with a young girl named Mizuki, and the three of them, along with Amame, became a close group of friends. By the beginning of 2019, the idol A-set was ready to appear publicly.

The main differences between Game Iris and "Prime Iris" comes sometime around 2018, where Renju Okiura met with Kotaro Uchikoshi at a bar. During a conversation, Renju introduced Iris to Uchikoshi, and his interest in her led to him become Iris's second producer. He introduced Iris at Anime Expo 2018 in his panel for his upcoming game AI: THE SOMNIUM FILES, and by January Uchikoshi introduced her to the world in her YouTube channel.

Prime Timeline[]

A-set's Career[]

On January 30th, 2019[4], Iris uploaded her first two videos as A-set, one serving as her introduction video, and the other being her first official music video. After both videos were released, Iris spent a week practicing and working at Lemniscate for her incoming videos.[5]

For her second video, A-set filmed herself at the Lemniscate offices, vlogging about the company, her favorite snacks and mascots, and various trivia about Egyptian mythology, uploaded on February 6th. The day after, A-set had already gained 1,000 subscribers to her channel.[6] On that weekend, she celebrates National Pizza Day by eating some pizza[7], and she watches the Grammys longingly wishing to be upon the stage[8].

In anticipation for Valentine's Day, Iris received many gifts and chocolates from her many fans. One of her gifts was a long poem from Ota sent to her via To-Witter,[9] confessing his feelings to Iris. On Tuesday, February 12th, Iris and Ota went to Sunfish Pocket to film for the next video, where she vlogged about the restaurant and opened up her chocolates and gifts. She eventually read Ota's poem out loud to her viewers, the contents of which creeped her out to some extent. While Ota tried to profess his feelings more clearly, Iris interrupted him and ends the video. The video is uploaded the next day, February 13th, the day before Valentine's Day, edited by the Lemniscate team. The day after Valentine's Day, A-set gets a bad stomach ache in the evening from all the chocolate she ate.[10]

On Monday, February 18th, before her next scheduled date, Iris contemplates doing an urban expedition around Tokyo for her next video.[11] On Tuesday night[12], Iris ventures out to the abandoned amusement park to film her video, where she vlogs about the incident that closed down the park, the urban legend of the missing child, and the secret society/cult NAIXATLOZ. During the video, Iris was under the impression that someone was nearby, hiding from or watching her. Ota, worried for her safety, tried to get in contact with Iris during her expedition, but failed to reach her.[12] Iris finishes editing and uploading her video of her expedition, but sometime during the upload process,[13] a threatening message is engraved into the video to stop broadcasting when talking about NAIXATLOZ. The strange circumstances behind what happened in her video kept her traumatized during the night, but she received comfort from Ota, calming down.[13] The next day, the two of them spent it traveling around Akihabara.[14]

During this time, Iris was interviewed, alongside Kotaro Uchikoshi, by GameSpot over her idol debut, giving herself more presence in the news. On the day the interview goes live, she begins planning out a trip to the Matsushita Diner for her next video, and a tweet from a fellow fan raises her interest in making a cover for the song "Sand Planet" from Hatsune Miku. A few days later, Iris and Mizuki go to visit Ota at the Diner, where the spend the day hanging out. Once Mizuki and Ota leave the restaurant to buy snacks next door, Iris prepares herself and films her next vlog video, where she talks about the restaurant and its legacy, her history with Mizuki, and the secret organization NAIXATLOZ from the previous video, delving deeper into the conspiracy theories surrounding the cult, such as the artificial reality theory. For the next couple of days, Iris edits her upcoming video, and uploads it at its scheduled timing, only for the video to become corrupted during the portion about NAIXATLOZ and the artificial reality, engraved with another message about this being her "final warning." Panicked, Iris contemplates deleting her altered video from her channel, but decides to instead change her passwords for her online accounts, in case they had been comprised. She goes offline once Ota arrives at her place to check on her, who spends the night comforting her and convincing her that these hacks are pranks organized by online haters. By the next day, Iris is pumped and celebrating having reached 1,000 followers on To-Witter, and the day after she's happily spending lunchtime with Mizuki, and later watches the Spike Chunsoft livestream for their game Zanki Zero: Last Beginning.

Within the following days, Iris begins prepping for her next two videos, taking trips throughout Tokyo to film for her next video and planning to buy Danganronpa-themed chocolate gifts for the White Day video the week after. For her trips, she took a camerawoman around to film her as she traveled to Ikume Shrine, Golden Yokocho, Harbor Warehouse District, and an unknown mansion. As she worked on this, Iris was invited to the Spike Chunsoft panel at GDC over in San Francisco, where she would be giving a convention report about all there is to see at GDC. Once Iris began uploading her touring video, the file got corrupted once again, cutting off the ending portion of the video. When Iris went to reupload the video, she found that the original file had been deleted from her computer. Convinced this was a continuation of the pranks from the previous videos, she proceeds to ignore these glitches and carries on.


Days later, she spends International Women's Day eating dinner with her mom, and some days later she takes suggestion on To-Witter on what to do for her next video. She works on her White Day special video, and by Monday she backs up her videos in the system to avoid any further deletion. On Tuesday, Iris leaves home and heads towards the airport, where she was to board a plane and head towards San Francisco. However, by Wednesday, her White Day video is not uploaded; instead, a video of security footage from inside Iris's home is shown, which prompted many strong reactions from her fans and acquaintances. Ota, Uchikoshi, and Hitomi all attempted to make contact with her, but no one could reach her.

Iris Sagan, unconscious and with a missing eye, moments before her death.

Iris had seemingly gone missing after leaving her home for the airport on Tuesday. In truth, she was kidnapped by a person dressed in a polar bear costume, whom apparently gouged out her left eye and murdered her. Her death was recorded and uploaded to her own channel on March 20th, titled "rw nw prt m hrw," one week after her kidnapping.

Impostor Timeline[]

This section is a stub. Expansion needed.

In a separate timeline, also on March 20th, a week after her kidnapping, an impostor of A-set is seen roaming the halls of Moscone Convention Center for GDC, where she spends time with Uchikoshi, who had located her by that point, at the Spike Chunsoft booths and all throughout San Francisco. Within the next few weeks, this impostor pretends to be A-set as she resumes the Lemniscate video series, with the events of the video "rw nw prt m hrw" never acknowledged.

Alpha Timeline[]

Return to YouTube[]


Playthrough of AI: THE SOMNIUM FILES[]






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
Appears Appears Appears Appears Appears Appears
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 Appears 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!
Appears Appears Appears Appears Appears Appears
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
Appears Appears Appears Appears Appears Appears
AI: THE SOMNIUM FILES Let's Play Part 2! Ota is here!!!



  • The word Iris in English can refer to the colored membrane found inside an "eye." The word Sagan in Japanese (左岸) means "left bank." Together, these terms essentially makes the phrase "left eye," which is a key aspect of her character and the events of AI: THE SOMNIUM FILES, as the left eye is what the serial killers the Bloody Polar Bear and the Cyclops remove from Iris and all of their other victims, making it a key theme of the game.
    • Her last name Sagan, when used as a given name, could also be written using 眼, the kanji for "eye," which continues the eye-themed trend surrounding her name and the game.
  • The name Iris is based on the Greek goddess Iris, goddess of rainbows and the messenger to the gods. According to Kotaro Uchikoshi, a rainbow also acts as a "bridge" to heaven, and as such, Iris's role in the story is meant to be as a "bridge" between our real world and the universe of AI: THE SOMNIUM FILES.[15]
    • A-set derives from the name "Aset," the original name of the Egyptian goddess Isis, connecting to the Egyptian mythology theme that the series seems to have. Iris states that her Uncle suggested the name "A-set" to her, due to how its believed that the goddesses Isis and Iris could be one and the same across two mythologies.
  • The 'fan-given' nickname Tesa is a reflection of the name A-set, which coincides with the game's theme of reflections.[15]
    • Originally, the Localization team were planning on localizing A-set's nickname to "Ace" instead. However, the idea was rejected because the name Ace had been used for a character in a previous game by Kotaro Uchikoshi: Zero Escape: Nine Hours Nine Persons Nine Doors.[15]
  • The Japanese version of her nickname is Aseton, based on adding the honorific "-ton" to the A-set name, which sounds similar to "acetone", a flammable chemical solvent found in nail polish.[15]



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. Ota's Valentine Poem
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 Lemniscate English channel About page
  3. 3.0 3.1 In the video "Uchikoshi Introduces Net Idol A-set!", Kotaro Uchikoshi says that Iris Sagan is 18 years old, with the channel's description supporting it, along with the date Oct. 26th, suggesting Iris would be 19 years old when AI: THE SOMNIUM FILES begins. However, months later, a Weibo account for A-set was made that featured her birth date as Oct. 26, 2001, meaning that she's presently 17 years old (and 18 when AI: THE SOMNIUM FILES begins). In the game itself, in the 2nd chapter, "saikAI", Iris says that she "turned 18 this year". With the game being set in November, and her birthday set in October, it means that she has been 18 for less than a year in-game. With the game's canonicity taking precedence over any other material, this means that the information above was simply a mistake, and that Iris is 17 in the many months of her career leading up to the release of the game.
  4. Timeline of events during A-set's career
  5. To-Witter Archives 2019 (Tesa): February 1st
  6. To-Witter Archives 2019 (Tesa): February 7th
  7. To-Witter Archives 2019 (Tesa): February 9th
  8. To-Witter Archives 2019 (Tesa): February 10th
  9. To-Witter Archives 2019 (Tesa): February 13th (1st half)
  10. To-Witter Archives 2019 (Tesa): February 15th
  11. To-Witter Archives 2019 (Tesa): February 18th
  12. 12.0 12.1 To-Witter Archives 2019 (Tesa): February 20th (1st half)
  13. 13.0 13.1 To-Witter Archives 2019 (Tesa): February 20th (2nd half)
  14. To-Witter Archives 2019 (Tesa): February 21st
  15. 15.0 15.1 15.2 15.3 GameSpot: How AI: The Somnium Files Blends Absurdism, Love, And Dreams Into A Murder Mystery
  16. Ari Advincula's tweet about leaving Spike Chunsoft
  17. 17.0 17.1 17.2 17.3 Tesa's Top 3 Favorite Snacks and Mascots!
  18. To-Witter Archives 2019 (Tesa): February 16th
  19. To-Witter Archives 2019 (Tesa): February 19th
  20. To-Witter Archives Aseton: June 24th
  21. 21.0 21.1 To-Witter Archives 2019 (Tesa): March 5th
  22. To-Witter Archives 2019 (Aseton): February 2nd
  23. To-Witter Archives 2019 (Aseton): February 8th
  24. To-Witter Archives Aseton: Crypt of Aseton
  25. To-Witter Archives Aseton: Aseton of Hyrule
  26. Famitsu article for GDC (translated by pennelini)
  27. To-Witter Archives (Tesa): June 17th