Ayumi Usubara

Ayumi Usubara (臼腹歩美, Usubara Ayumi) is a former hit-man of sorts of the Futsuku Group where he worked under Adamura. The Futsuku group was disbanded after Izaya caused the end of Bunokura. Since the disbandment, Ayumi and his step-mother Yuuki, have been hunting down both Izaya and Sozoro for revenge.

Characteristics
Nicknamed "The Feudal Lord’s Pet Whale" & "The Blue Whale Baseball Stadium Destroyer", Ayumi is described as having many scars on his face which is mostly covered by black bandages, dyed blue hair, and is frequently seen wearing a business suit. Ayumi is also known to be 'not the brightest', and extremely quiet. He is someone who knows only violence.

According to rumors, Ayumi is known to have taken down a boar by lifting a vending machine and dropping it on the boar, he's also known for his ability to lift vending machines, although he cannot throw them. He is also known for going into blind rages, at least once in the novels he injures a woman, though he does not remember doing so afterwards and feels bad about it.

A Sunset with Izaya Orihara
As a former hit-man of sorts for the Futsuku group in Bunokura, Ayumi worked under Adamura where he was known as "Adamura's/Feudal's Lord's Pet Whale". The exact nature of his former occupation is unknown, though he was sort of the muscle for the group.

However, after Izaya began leaking information and gossip, the dried-up Bunokura mine which his employer owned, closed down. The Futsuku group vanished following the events of the Sunset novel.

A Standing Ovation with Izaya Orihara
After the city Bunokura goes under and the Futsuku Group disperses, Ayumi vows to get his revenge against Izaya and Sozoro. He returns home and explains the details of what has happened to his step-mother Yuuki, and after some scolding she agrees to help him track down Izaya. Waiting on any leads regarding Izaya's location, Ayumi and his step-mother wander around the Kanto region when they happen to see Izaya and Sozoro on the television broadcast of the baseball game taking place at a ramen shop. Yuuki listens closely to the broadcast and informs Ayumi they seem to be at the Natsugawara Stadium and take a taxi to get there as soon as they can.

Trivia

 * Ayumi is usually a girl's name and literally means "walking beauty."
 * The only quoted words he has said are "Izaya Orihara."