PHHeroes and villains are two sides of the same coin... I can see it in that glare of yours. So what is it that really makes someone a hero?
Tsunagu Hakamata (
Tsunagu is a tall man with dark eyes and blonde hair combed into a side-part. In his hero costume, the majority of Best Jeanist's body is clad in denim. He has the waist of jeans shaped into a cylinder to covers his mouth and a jean jacket with sleeves. Best Jeanist finishes his outfit with a pair of jeans and brown boots. As shown on several occasions, he has unnaturally long and flexible neck.
Tsunagu is an elegant man with flamboyant tendencies. He believes very strongly that people with influence must maintain a positive appearance both physically and socially. Best Jeanist often uses metaphors referencing jeans or denim. He often inspires his recruits with speeches by telling them to keep their life straight like their jeans. 
Best Jeanist takes the role of being a hero very seriously. He is selfless, brave, and charismatic. Best Jeanist aims to spread a sense of a peace to all people and believes hero's don't make excuses. He did not hesitate to take the full brunt of All For One's attack to save his allies, something the latter later praised him for.
Some time ago, Best Jeanist was called into a meeting with Eraserhead, Manual, Death Arms, Snipe, Thirteen, Endeavor, Air Jet, Midnight, Ingenium, Gunhead and a member of the police force to speak about the unwilling civilians injected with Trigger.
When Katsuki Bakugo chooses him for an internship, Best Jeanist introduces himself by admitting he does not like Katsuki very much. Irritated, Katsuki replies that Best Jeanist sent the offer to him. Best Jeanist says all his other recruits were well behaved unlike him. Although Best Jeanist admits that Katsuki has outstanding talent, he says the young man still needs to be taught how to display himself as a hero. Irritated Katsuki approaches Best Jeanist, forcing him to discipline Katsuki by using his Quirk to wrap him in denim.
The next day, Best Jeanist tries to teach Katsuki the value of maintaining an elegant outward appearance. Best Jeanist styles Katsuki's hair similar to his own, but it returns to its messy form shortly after.
After Hero Killer: Stain's defeat is published, Best Jeanist reminds Katsuki and all his sidekicks to remain calm and operate as they normally would. Later on, Best Jeanist takes Katsuki on patrol. He asks Katsuki why patrols are important, to which he answers it's because they can beat up criminals on sight. Best Jeanist says this answer is wrong, and that patrols help heroes maintain a strong public image. Katsuki ends up getting into a spat with young children, making Best Jeanist comment about Katsuki's pride.
Following the abduction of Katsuki Bakugo, Best Jeanist is recruited by Detective Naomasa Tsukauchi. Naomasa enlists Best Jeanist to the Hideout Raid Team, a fighting force tasked with infiltrating the League of Villains hideout in Kamino Ward. Alongside Edgeshot, Endeavor, Gran Torino, Gang Orca, Tiger, Mt. Lady, Kamui Woods and All Might, Edgeshot attends a strategy meeting to rescue Katsuki Bakugo from the villains. 
The Hideout Raid mission commences the next night. Just prior to the mission, Best Jeanist reminds Endeavor that he's an alumni when the latter complains about participating. Best Jeanist shares with everyone that he had Katsuki as an intern. He worries that Katsuki's attitude might get him into trouble. Gang Orca is surprised that not even the elegant Fiber Hero could get through to him.
Best Jeanist leads the second squad to the Nomu production factory. Gang Orca and Mt. Lady help him successfully secure all of the Nomu. Best Jeanist restrains the majority of them with denim strings using his Quirk. Mt. Lady complains about the simplicity of their task. Best Jeanist explains that the difficulty of the task doesn't take away from its importance. The hideout team is interrupted when a shadowy figure appears from the dark. Best Jeanist quickly restrains the man by tightening the fibers of his clothes. Mt. Lady expresses concern for the man but Best Jeanist states he can't give the villains any slack. The villain frees himself and aims a large explosion as Best Jeanist and the squad.
Best Jeanist manipulates his allies clothes and pulls them out of danger. He takes the brunt of the evildoer's blast and lies injured on the ground. The man levitates towards the Fiber Hero and commends his efforts to protect the other heroes. Best Jeanist recognizes the man is the leader of the League of Villains. He knows that this man's strength is comparable to All Might's, but believes that's no excuse not to act. Best Jeanist attacks, but is easily countered and crushed by an air cannon from All For One. 
Defeated, Best Jeanist falls unconscious. He's later rescued when All Might, Endeavor, Edgeshot, and Kamui Woods arrive to defeat All For One. 
Then, in the second annual of the Hero Billboard Chart JP, Best Jeanist appears on stage, where the announcer reveals he is taking a rest from his duties as a Hero for an extended amount of time. It is also revealed he has climbed to from No. 4 to the No. 3 spot due to his participation in the Kamino Ward Hideout Raid.
Enhanced Durability: Tsunagu was able to take a direct hit from All For One's attack and remain conscious, albeit taking heavy injuries.
Fiber Master (ファイバーマスター Faibā Masutā?): Best Jeanist can manipulate fibers at will as long as the person is wearing clothes. He can unravel a part of his clothes into fabric strings and can use them to restrain targets. This Quirk works better on denim rather than sweats. This is a powerful ability that catches most off guard. He can manipulate his threads to move very fast, far, thin enough to be nearly invisible, and strong enough to easily bind even Nomus.
- His name contains the kanji for "hakama" (袴?), "field" (田?), and a component of the word "fiber" (維?).
- His given name is homophonous with the verb "to tie or fasten".
- Best Jeanist's favorite animal is the wolf.
- In series, Best Jeanist leads the fashion world with huge popularity among both young and middle-aged men.
- (To Katsuki Bakugo) "Heroes and villains are two sides of the same coin... I can see it in that glare of yours. So what is it that really makes someone a hero?"