Koichi Haimawari, later known as The Crawler and formerly called Nice Guy, is the main protagonist of the spin-off series My Hero Academia: Vigilantes. At the start of the story, he is a nineteen-year-old college student working a part-time job at a convenience store, living in a modest apartment and passing his time by performing small acts of kindness for strangers in his neighborhood. His unlicensed hero activities begin even before he formally adopts the vigilante identity, as he habitually helps people carry groceries, give directions, or pick up litter. His decision to become a more active vigilante is set in motion when he and the street performer Kazuho Haneyama are attacked by thugs and rescued by the hardened vigilante Knuckleduster, who later recruits him to form the Naruhata Vigilantes group.

Koichi has an easygoing, mild-mannered personality and is genuinely generous, rarely expecting anything in return for his help. He often fails to pick up on social cues, which leads others to regard him as slightly odd or even creepy, both among his university peers and among the public who encounter The Crawler. Despite this, he possesses a strong and quiet sense of justice, and his desire to help others is the core of his motivation. He does not seek fame or power; he simply wants to protect the people around him and make his community safer, even if he must operate outside the official hero system.

In terms of abilities, Koichi’s Quirk is called Slide and Glide. It allows him to generate ring-shaped repulsion fields from his hands and feet. When he places at least three of his limbs on a surface, he can slide across it as if skating on ice. Initially, his Quirk seems modest: he can glide along the ground and up walls, but he lacks speed, aerial mobility, and offensive power. Through training and real combat experience, he gradually expands his capabilities. He learns to brake and accelerate after receiving guidance from the Pro Hero Ingenium, enabling him to move at high speed with control. He develops the ability to hover in midair, propel himself short distances, and unleash repulsion blasts from a single hand, which can knock back opponents or damage objects. By the end of the manga, he achieves full flight, can match the speed of the extremely fast Overclock Quirk, and can create repulsion shields for defense. His Quirk is well suited to his evasive, non-confrontational style of heroism, emphasizing mobility and quick escapes rather than brute force.

Koichi’s role in the story is that of an everyman who steps into the gap left by the professional hero system. The series takes place five years before the main My Hero Academia timeline, and Koichi represents the ordinary citizens who choose to act when licensed heroes are unavailable or overlook small-scale crime. He starts as a timid, self-doubting young man and grows into a confident vigilante who earns respect even from Pro Heroes. His journey is personal rather than world-ending; he deals with drug dealers, traffickers, street-level villains, and a major conspiracy surrounding a dangerous drug called Trigger. Through it all, he remains principled and compassionate, often trying to understand his opponents rather than simply defeat them.

Key relationships define his growth. Knuckleduster serves as a tough but caring mentor, pushing Koichi to become stronger and teaching him the realities of vigilante work. Kazuho Haneyama, better known as Pop Step, is his close ally and eventual love interest; their bond deepens as they fight together and support each other’s dreams. Koichi also develops a rivalry with the villainous Number Six and later forms a professional partnership with the Pro Hero Captain Celebrity, eventually becoming his sidekick under the new alias The Skycrawler. Throughout these connections, Koichi’s innate kindness and resilience influence those around him, turning former enemies into allies and inspiring others to act on their own sense of justice.

Koichi’s development is marked by his gradual accumulation of confidence, skill, and responsibility. He begins unsure of his worth as a hero and prone to hesitation. Over the course of the series, he learns to trust his instincts, push his Quirk’s limits, and stand firm in the face of danger. By the end of the story, he has transformed from a shy college student who merely helped people on the street into a capable vigilante who plays a central role in the Naruhata Lockdown crisis and later transitions into legitimate hero work as a sidekick. His arc underscores the idea that heroism is not defined by official approval or overwhelming power but by the willingness to act selflessly for others.