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Dier Quotes
Full name Dier
Affiliation Squad 404
Voice actor Fukuyama Jun
Artist Unknown
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"This is classified information!"

This article contains unmarked spoilers. You have been warned.

Dier is a young genius Doll technician and a long time collaborator of Squad 404. He is also the younger brother of Sier. While he's a background character in the main story, he makes a memorable appearance as a main character in the Bounty Feast event under the identity of Dima.


At some point, Dier hired SMG UMP45Thumb button.pngUMP45  and SMG UMP9Thumb button.pngUMP9  to combat a Dolls kidnapping gang in his home city. 45 and 9 ended up helping HK416 and an abandoned maid Doll against two of the kidnappers,[1] and with the help of 416's high combat specs, they neutralized 18 thugs in their own base and let the police pick them up, with Dier's anonymous manifesto against police corruption later being shared in the news. After 416 accepted to take care of the Doll she had saved, she asked Dier to make her a T-Doll.[2] Being the same model as the maid Dolls in his parents' mansion, and the same model as the first Doll he had ever worked on,[3] Dier upgraded her as best he could and outfitted her with a custom fire control core and a weapon from his personal collection, christening her AR G11Thumb button.pngG11 .[2] However, he had to make several tweaks before her neural cloud stopped crashing intermittently from the load of her advanced fire control core.[4]

Character Info

Dier is the son of a rich family and a self-proclaimed genius in Dolls engineering, calling himself the “Almighty Mechanic”.[5][6] He is one of the rare Dolls technicians capable of disabling the core order preventing Dolls to attack a human being.[1] Dier treats his repair work as restoring an art piece by being minimally invasive and destructive, he believes that Dolls have a right to dignity and that traffickers who kidnap, dismantle and resell Dolls after wiping out their memories are a disgrace to his line of work. Sier is Dier's older sister, and considering his poor accounting skills he mused about making a Doll replica of her, since his sister was occupied with her own business.[2] Sier later worked as Dier's accountant while also doing the tasks Dier shouldn't, such as handling female Dolls clothing.[3] Sier care about and sometimes impart tough love on her younger brother, but when asked about their radically different hair color, Sier hints that there is more to the sibling's past than it appears.[7]

Dier is the main technician of Squad 404 and performs maintenance, repairs and upgrades on their neural clouds and bodies in his own workshop at his parent's mansion, or in underground workshops near the squad's areas of operation. He also provides remote tech support in emergencies. While getting handsome rewards for his work, Dier is regularly bullied into underselling his work by 404, especially by 45. Since he could easily get by with his normal line of work as a Doll technician, 404 is a kind of passion project for Dier.[3] 404 suspects Dier to find a salacious interest in working with Dolls, and though he always denies it,[4] his fascination with maids sometimes get the best of him.[2] Both Dier, Sier and their maids enjoy video games.[8]

Dier can be selected as an adjutant on the main menu, but some dialogues indicate that he is the original and others that he is an A-Doll he created in his own image. It is worth pointing out that Dier and the Commander don't know each other in the core stories, so like other NPC adjutants besides Kalina, this adjutant's existence shouldn't be considered canon.

Story Involvement

Main story

To prepare Squad 404 for their mission to recover the drone containing data retrieved by AR M16A1Thumb button.pngM16A1  that Dreamer shot down over Area S15, Persica had Dier travel to the basement of a small cafe to perform heavy-duty maintenance on 404 and outfit them with an electronic interfacing protocol upgrade pack for better electronic warfare performances.[9] 9 asked Dier to remotely monitor 45's neural cloud,[10] which helped them intervene early when 45 fell under the influence of the Parapluie virus.[11] Dier then remotely repaired her shattered consciousness after Dreamer's attacks.[12]

Though Dier does not appear in the story explaining AR ST AR-15Thumb button.pngST AR-15 's neural upgrade, Sier does, implying that Dier was hired by Angelia to repair and upgrade her.[13]

After 45 suffered a grievous injury by protecting 416 during the battle of the Sangvis Ferri HQ, Dier remotely assisted in emergency repairs at the temporary Griffin & Kryuger base, with Kalina providing a temporary power supply to keep her core modules alive and stabilize her before she was transported to Dier's workshop for repairs.[14] Despite her usual maintenance already being difficult due to her model having been pulled out of the market long ago and the her own body having been extensively modified, 45 insisted that she would rather die than accept a new body and lose the memories of SMG UMP40Thumb button.pngUMP40  stored on Level III of her neural cloud.[15]

Digging deep in his depot for spare parts compatible with 45, Dier managed to replace her right arm with a bulky ancient model, jury-rigged with spaceship-grade duct tape and retaining exposed wires to maintain the conduction and cooling levels necessary to retain movement speed. He couldn't find a replacement for her left eyeball and installed new sensors to compensate for the loss of vision. He however managed to greatly expand her neural cloud and body frame capacity, install an signal amplifying antenna in her skull to boost her network connectivity and electronic warfare capabilities, and greatly extended her internal battery life. 45 took the job to rescue the Commander from Paradeus as thanks for providing the transport that brought her to Dier, and to pay for Dier's work.[16] During the mission and later ones, she used one of Dier's module installed in her arm, dedicated to the hacking of Nytos.[17]

Dier later upgraded HK416 and UMP9's bodies so they could take part in the battles of Talinn and the Paldiski Submarine Base, the squad using the pay from these missions to pay for their refits.[18] Making the best of her wealth of free memory space, he outfitted 416 with a new grenade launcher module, a multi-thread processor upgrade dedicated to electronic warfare and the latest model of dual-purpose neural cloud attack barrier.[3] He was pressured by 45 into outfitting 9 with new electronic warfare capabilities, necessitating the use of his personal lab.[6]

After 404's mission in the ruins of Zeratul-Worcester Pharmaceuticals, G11 asked 45 to appoint her for an upgrade. Dier changed her fire control core and increased her neural storage, which freed power for her personality emulation module to function correctly and enabled her original personality to manifest instead of being stuck in the low-power lethargy that had become her normal state. Dier equipped her with an external battery to compensate for the heavier power consumption,[19] but mistakenly gave her a battery with a higher output than needed, overclocking her neural cloud[20] and causing her to go hyperactive, even stealing some of the work of Dier's maids and running away from Dier's workshop. 416 eventually found and fought G11 until her external battery was out of power, enabling Dier to change it for a less powerful battery, freeing some storage space in the external casing and also installing a switch to overcharge G11 at will. He was forced to carry G11's external battery all the way back to his workshop as punishment for his mistake.[21]

Bounty Feast

Dier started playing The Division, roleplaying as a female character called Dima and using a neural cloud backup of 416 as an ally, called AR Agent 416Thumb button.pngAgent 416 . After being derided by Agent 416 for being bad at the game, Dier tried to tweak her character to make her friendlier but caused it to integrate with the game's data, turning her into Fang, a new boss affiliated with the Last Man Battalion. The bug also turned on the safe mode of Dier's VR headset, which would cause it to lose all of his game data if he tried to forcefully disconnect. The only way to exit safe mode would be to delete Fang's data by killing her in the game, which Dier couldn't do by himself.

After he found out how to send messages on the internet from the game, Dier contacted two T-Dolls to join and help him take out Fang. Embarrassed to be found roleplaying a female character, Dier passed Dima as an NPC, but they still couldn't beat Fang.[22] The two Dolls, AR RFBThumb button.pngRFB  and AR MDRThumb button.pngMDR , took to Grifchan and advertised a tournament with a fake 10 million dollars cash prize to recruit more players and beat the game.[23] From the unexpected newcomers, Dier copied AR VectorThumb button.pngVector 's data as the most efficient player to create a new ally called AR Agent VectorThumb button.pngAgent Vector , but the copy was corrupted by Fang and became Hellfire, aligned with the Cleaners, creating a second boss to destroy. When Dier broke character as the end of the tournament approached, the real 416 recognized him, and after her and Vector defeated their alter egos and remained as the last survivors, they forced Dier to reveal the truth. Dier explained and pleaded to the two Dolls not to reveal he had been “cross-dressing”, but he didn't know that the tournament was being broadcast to Griffin's base, provoking general hilarity among the Dolls, pity from the Commander, disgust from G11 and UMP9, and unspeakable fury from UMP45 who immediately set out to beat him up. 416 eventually offed Dima with a bullet to the head after learning there was no real cash prize for the tournament. Sier sent a formal letter of apology to the Griffin base the day after.[22]

In his adjutant dialogues, Dier laments that his humiliation gave him trust issues and that he could have avoided it if the Commander had taken part in the game. He also reports that the Dolls dedicated a restroom to Dima to bully him.



  • Dier and Sier's names in the original script are pronounced as Déěr (德尔) and Xīěr (希尔). In the game's files, they appear as Deele and Seele, probably as a wordplay on the expression “seal the deal”. In the original English script for Deep Dive, they appeared as Deele and Zeele. Starting with Singularity, their names were updated to Dier and Sier.
  • It seems Dima found her way into Griffin and Kryuger sometime in April... How? She even left a message in the inbox, along with 100 Calibration Ticket, 1 Sweet Explosives and 10 Ice Cream Cone:

A Message from an Unknown Domain

Hi~ Agent, long time no see.
You probably still remember our brief encounter in Manhattan? That's right. I was the contact. I know this is hard to believe - but I'm ready to spend some time at your company.
I bet this brings back memories. I feel you...
But let bygones be bygones. We shouldn't stop moving forward. Let's leave the past behind and just forget what happened! Yep, forget everything! That way, we can get along with each other. I hope my little visit will go well.
Happy holiday, by the way! Enjoy the special day!



  1. 1.0 1.1 Girls' Frontline, AR HK416Thumb button.pngHK416  Neural Upgrade story 2
  2. 2.0 2.1 2.2 2.3 Girls' Frontline, AR HK416Thumb button.pngHK416  Neural Upgrade story 3
  3. 3.0 3.1 3.2 3.3 Girls' Frontline, AR HK416Thumb button.pngHK416  Neural Upgrade story 4
  4. 4.0 4.1 Girls' Frontline, AR HK416Thumb button.pngHK416  Neural Upgrade story 1
  5. Girls' Frontline, Deep Dive, E3-4
  6. 6.0 6.1 Girls' Frontline, SMG UMP9Thumb button.pngUMP9  Neural Upgrade story 1
  7. Girls' Frontline, Sier adjutant dialogue
  8. Girls' Frontline, Dier and Sier adjutant dialogues and AR HK416Thumb button.pngHK416  Neural Upgrade story 4
  9. Girls' Frontline, Deep Dive, E1-1
  10. Girls' Frontline, Deep Dive, E2-1
  11. Girls' Frontline, Deep Dive, E2-4
  12. Girls' Frontline, Deep Dive, E3-1, E3-3, E3-4
  13. Girls' Frontline, AR ST AR-15Thumb button.pngST AR-15  Neural Upgrade story 3
  14. Girls' Frontline, Continuum Turbulence, E2-1, E2-2
  15. Girls' Frontline, SMG UMP45Thumb button.pngUMP45  Neural Upgrade story 2
  16. Girls' Frontline, SMG UMP45Thumb button.pngUMP45  Neural Upgrade story 4
  17. Girls' Frontline, Shattered Connexion, E2-2
  18. Girls' Frontline, Shattered Connexion, E1-2
  19. Girls' Frontline, AR G11Thumb button.pngG11  Neural Upgrade story 1
  20. Girls' Frontline, AR G11Thumb button.pngG11  Neural Upgrade story 2
  21. Girls' Frontline, AR G11Thumb button.pngG11  Neural Upgrade story 4
  22. 22.0 22.1 Girls' Frontline, Bounty Feast, Chapter 5: 1:10 Extraction Point
  23. Girls' Frontline, Bounty Feast, Chapter 0: The Night Before