Igor is a russian assassin hired by Nebula (specifically Shingen Kishitani ) to capture the serial killer Hollywood for experimentation. After the incident with Hollywood, he continues to reside with Ikebukuro, mostly seen hanging around Russia sushi or helping the Orihara Twins with their shopping (mostly as their pack mule).
Not much is known about Igor's physical appearance other than the fact that he is caucasian and that he is extremely tall. He is regarded as the seventh deadliest assassin in Russia and is capable of using literally anything as a weapon (he once slit an ex soldier's throat with a piece of paper). Thus, Igor never brings his own weapons into battle.
Despite his violent reputation and intimidating aura, Igor behaves like a gentleman. He always addresses others, especially clients, with respect. After Mairu and Kururi pay for his medical bills despite having just met him, he agrees to help them meet the black motorbike out of gratitude. Igor is also very cautious. He never meets with a client directly and rarely ever deals with the same one more than once (at least not under the same name). Aside, possibly, from Shingen, no one is able to establish regular contact with Igor. Igor is also known to seek out his client himself, they never come to him.
He is hired by Nebula to capture the serial killer "Hollywood" (who is actually Ruri Hijiribe ) and meets with Shingen Kishitani to discuss the details of the job. While they talk, they come across Anri Sonohara who is frozen in fear by Igor's pressence. Igor tries his best to calm Anri down and places a comforting hand on her shoulder but it only seems to make things worse. Unbeknownst to even Anri, Saika acts on it's own and stabs Igor's hand through Anri's shoulder, turning him into one of her childrenThe next night, Igor lures Ruri (dressed as a zombie) into the park and the two begin a fierce struggle. Along the way, Igor spots a metal briefcase and grabs it to use against Ruri. The brief case ends up smashed to pieces and is revealed to be owned by none other than Shizuo Heiwajima . Mistaking Igor and Ruri as robbers, Shizuo hits Igor with a park bench which immediately incapacitates him. Tom Tanaka gives Igor an "official" welcoming into Ikebukuro and tells him to seek out help at Russia Sushi.
Igor stumbles through the back alleys of the city until he comes across Mairu and Kururi. The two of them manage to take Igor to Russia Sushi where Dennis calls in Shinra to patch him up. Igor initially mistakes Shinra for his father but immediately realizes his mistake. Shinra charges the owners with a whopping 200,000 yen for such a sudden call and no one is able to pay for it except for Mairu and Kururi who managed to find celty's 1 million yen that she had lost, earlier. In return for paying Shinra, Dennis, Simon , and Igor agree to help the twins meet Celty. Dennis calls Celty to have her carry around a large bag with Igor hiding inside. The plan is that Celty would eventually reach her home and Igor would contact Mairu and Kururi with it's location so that they could visit Celty themselves.
The plan is unfortunately ruined by the arrival of Toromaru who chase Celty along with Kyohei , the van crew, the twins, Anri , Mikado , and Aoba across the city. After they reach an overpass, Igor bursts out of the bag and tries to hold off the Toromaru members while everyone else escapes. He is also assissted by Ruri who witnessed the incident on the news. After the incident blows over, Igor decides to take a vacation for an indefinite amount of time. He is last seen helping Mairu and Kururi shop for clothes.