The team was originally formed by Knuckleduster to end the drug trafficking of Trigger in Naruhata as well as fight those people who become Instant Villains for consuming Trigger. In doing so they are also tasked with patrolling and protecting Naruhata from thugs and minor villains unrelated to the Trigger.
When they are not patrolling together, each member acts independently. The Crawler usually does all kinds of public services for no benefit to himself like picking up trash, pointing out directions to people, or return the lost objects to their owners among other things. Pop☆Step, meanwhile, seeks to gain fame and recognition by acting illegally as a street idol, although later she will do so legally.
Knuckleduster, for his part, pursues a personal vendetta. The Villain Factory, the organization behind the trafficking of Trigger and the Instant Villains, was responsible for ending his career as the Pro Hero O'Clock, stealing his Quirk, as well as attacking his family and kidnapping his daughter, turning her into the villain and drug dealer Kuin Hachisuka. Due to the dangerous nature of his personal mission, Knuckleduster keeps his true objective in secret to his allies to avoid endangering them.
The Naruhata Vigilantes is not a very powerful team, but the collaboration between its members and with the occasional help of an ally, have managed to overcome any obstacle and enemy they face.
Despite being Quirkless, due to his past as a Pro Hero Knuckleduster is the only one with the physique, knowledge, and experience necessary to fight, so he is always in charge of beating up villains until they are defeated. When he is working alone in his personal mission, Knuckleduster does not hesitate to use all kinds of items, dangerous devices, and firearms to defeat the threat.
The Crawler also fights and generally acts as support of Knuckleduster, since he is not very strong and his Slide and Glide Quirk is not too powerful. All in all, thanks to Knuckleduster's training and the experience he gains fighting villains, he improves notably in these aspects over time, discovering new abilities of his Quirk that make him more effective in combat. However, when fighting solo, his strategy to fight criminals and villains is doing what he can to buy time until someone much more competent appears to solve the problem.
Thanks to her Quirk Leap, Pop☆Step is usually the first to get to where there are problems, but because she has no combat experience, Pop does not usually participates in the fights against villains, but she helps her teammates in their missions in various ways: Investigating for them, helping to evacuate the passers-by, acting as a distraction or decoy against villains, providing first aid, calling for help, etc.
The team is formed when the Vigilante Knuckleduster saw potential in Koichi Haimawari when he tried to save Kazuho Haneyama from Soga Kugizaki and his friends. Knuckleduster offers Koichi to be his master and train him to become a true hero. Although Koichi rejects his offer at first, Knuckleduster insists on it and explains that their goal is to fight the drug distribution of Trigger and defeats the people responsible for it.
Koichi doesn’t want to be part of the Knuckleduster plan, especially after knowing his violent methods of investigating, but after confronting a Trigger dealer, he finally agrees to become in his apprentice and being trained into "The Crawler". Kazuho decides to also join the team to help them in the investigation. Sometime afterwards Knuckleduster takes Koichi's penthouse as a base, with Kazuho visiting them there often as well.
The three vigilantes face several Instant Villain, whom they defeat and leave tied up for the police to put them in prison. Their actions soon began to intervene with the plans of Kuin Hachisuka, an agent of the Villain Factory. Kuin considered them a nuisance to the objectives of the Villain Factory, and wants to get rid of them, although her mysterious boss advises her not to do so in order to exploit the Vigilante's constant interference to collect data in order to refine their experiments.
Following orders from his mysterious patron, Kuin continues to cause troubles to obtain data. Finally, she is defeated by Knuckleduster, who extracts the parasitic bee from his daughter's body and kills it, rescuing Tamao in the process. After this, Knuckleduster abandons the Naruhata Vigilantes watchers without saying anything to his two teammates, who since then have to fend for themselves when they face villains.