Kinnosuke Kuzuhara

Kinnosuke Kuzuhara (葛原金之助 Kuzuhara Kinnosuke) is, according to Shinra, a motorcycle police officer known for dealing with the most troublesome characters and thus was most likely brought in to capture Celty. He's especially known for going to insane lengths to get his man even if it means causing wrecks or anything of the sort. He is extremely persistent as shown when he and dozens of other officers chased Celty around the city for an entire day (an event which left her traumatized to the point that she runs as far away as she can if she so much as glances at him).

Characteristics
Kuzuhara is shown to be extremely adept at motor cycle riding, being able to keep up with Celty even when she uses her supernatural abilities. While not as strong or agile as other characters in the series, he is still very proficient at combat, even if he is forced to fight while riding his motorcycle. In terms of physical appearance, Kuzuhara's most distinguishing features are his read ascot, a pair of sunglasses and a cross shaped scar on his cheek. Aside from these, his attire is more or less the same as other traffic officers.

Personality wise, Kuzuhara is known to go to extreme lengths to make arrests and is almost zealous with maintaining order on the road. Even the numerous supernatural events around the city do little to faze him. Kuzuhara is also very proud of his position as a police officer and does his best to emulate the best qualities of his profession and as such, has a strong set of morals.

Saika Arc
He was mentioned to be one of the strongest men in Ikebukuro.

Yellow Scarves Arc
He is introduced in this arc chasing Celty around the city, eventually cornering her. Celty attempts to use her shadows to scare them off but, much to her surprise, he remains unfazed. Kuzuhara's actions later traumatize Celty and cause her to develop a fear of traffic cops. Kuzuhara later appears to stop Horada from escaping, arresting him for traffic violations.

Hollywood Arc
Kinnosuke Kuzuhara appears near the beginning of the arc grilling Celty about how her motorbike doesn't have headlights. The two begin yet another chase through Ikebukuro with Kinnosuke keeping up very well with Celty despite her using her supernatural abilities to her advantage (riding on walls to avoid traffic, etc.) This act is what brought so much attention from the media and is effectively what prompts the bounty on Celty's head to be placed (effectively making Kuzuhara the cause of Celty's woes throughout this arc).

He appears later and offers some unexpected assistance when Celty was being chased by Toromaru members. When one of the bikers takes a swipe at him, Kinnosuke proceeds to beat the living crap out every single biker around him despite being on a motorbike. Celty manages to lose him in the fight. He returns once more with a larger entourage of traffic cops but they aren't able to deal with the sheer numbers of the Toromaru members that are chasing Celty and Kyohei.

Dragon Zombie Arc
He appears briefly at the start of the first chapter, once again, chasing Celty. He passes a car Izaya and Shiki are talking in and Izaya comments on how Kinnosuke's relative, Yumeji Kuzuhara, is a member of the anti-yakuza branch of the police department.

Kadota's Coma Arc
Kinnosuke sees his niece (Shinju) and talks with her. Shinju tells him about Shizuo being put in a jail and then leaves.

Trivia

 * Kinnosuke has 2 sons
 * one son is in Mikado's class and is part of the schools disciplinary committee
 * His second son, Souji Kuzuhara, appears in Ryohgo Narita's other series "Etsusa Bridge" which is set 10 years after Durarara.