
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. 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. He is one of the rare Dolls technicians capable of disabling the core order preventing Dolls to attack a human being. Character Infoĭier is the son of a rich family and a self-proclaimed genius in Dolls engineering, calling himself the “Almighty Mechanic”. However, he had to make several tweaks before her neural cloud stopped crashing intermittently from the load of her advanced fire control core. 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, 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 G11 G11. After 416 accepted to take care of the Doll she had saved, she asked Dier to make her a T-Doll.

45 and 9 ended up helping HK416 and an abandoned maid Doll against two of the kidnappers, 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.


At some point, Dier hired SMG UMP45 UMP45 and SMG UMP9 UMP9 to combat a Dolls kidnapping gang in his home city.
