OVA
Description
Garō is a pivotal antagonist and anti-hero from the manga, known for his self-proclaimed title as the Hero Hunter and his ambition to become a human monster. He is eighteen years old and originally stood 177 centimeters tall, though his stature and appearance change drastically as he undergoes monstrous transformations throughout the story.

The foundation of Garō's ideology lies in his childhood. During his youth, he was forced to play the role of the villain in heroes versus monsters games with his peers. He was often pinned down, beaten, and humiliated simply for sympathizing with the monster characters. When he sought help from a teacher, he received none due to the popularity of the children bullying him. This repeated trauma, combined with a disdain for the simplistic morality of hero shows where the "unfair" hero always wins, led him to view the Hero Association and its values as the ultimate symbol of a rigged system that only protects the strong and popular. His goal became to overthrow this order and create a world of absolute evil, or as he terms it, an equal-opportunity terror where the weak are no longer protected by an unjust peace.

In terms of personality, Garō is intense, ruthless, and driven, yet he operates under a strict, self-imposed code. While he hunts heroes without mercy, he refuses to kill ordinary civilians or the arrogant criminals who lack conviction. His hatred is specifically reserved for the hypocrisy he perceives in heroes. Despite his claims of being a monster, Garō consistently displays a strong sense of honor and protection toward the innocent, particularly children. He often finds himself inadvertently saving people, and other characters note that his instincts are those of a hero rather than a villain, even as he verbally rejects that label.

Garō's role in the narrative begins as a direct threat to the Hero Association. After being expelled from his master's dojo for attacking his fellow students, he launches a campaign to hunt heroes of all ranks, from C-Class to S-Class. His actions attract the attention of the Monster Association, which sees his potential for evolution. He is captured and forced into their headquarters, where he becomes a central figure in the ensuing conflict between the heroes and monsters. Trapped between the two factions, Garō fights against both, serving as a chaotic force that pushes many S-Class heroes to their absolute limits. Ultimately, his path leads him to a climactic confrontation with Saitama, where his ideology is challenged at its core.

Key relationships heavily define Garō's journey. His former master, Bang, is an S-Class hero who still cares for his wayward disciple. Bang taught Garō the Water Stream Rock Smashing Fist, and their confrontations are filled with a sense of tragic paternal disappointment and lingering affection. The young boy Tareo is perhaps the most important figure to Garō's humanity. Garō sees his bullied younger self in Tareo, and despite his claims of being evil, he repeatedly risks his life to save the boy from danger. Tareo is the only person who truly believes Garō is a hero, serving as a tether that prevents Garō from completely discarding his human heart. His relationships with other heroes are also significant. He defeats Tanktop Master in his first major S-Class fight, has a fierce rivalry with Metal Bat where mutual respect is born, and brutally shatters Superalloy Darkshine’s confidence by pointing out that the hero is simply playing a role.

Garō undergoes an extraordinary character development arc that is physically manifested through constant evolution. He begins as a human prodigy martial artist but gradually experiences a limiter-breaking phenomenon. After suffering near-fatal defeats and refusing to stay down, his body begins to mutate. He transitions through several stages, including a half-monster form, a spiral form, and eventually a complete monster form characterized by chitinous armor and horns known as Awakened Garō. After being defeated by Saitama, who sees through his act and acknowledges his true nature, Garō is forced to confront his contradictions. His final, most powerful state is not achieved through his own will but by being granted cosmic power by a divine entity simply called God, transforming him into Cosmic Fear Garō, a being capable of manipulating nuclear forces and energy itself.

Garō is a martial arts genius of the highest caliber. Proficient in the Water Stream Rock Smashing Fist, he possesses the ability to deflect and redirect kinetic energy. His most terrifying ability is his reactive evolution and analytical mind; he can learn and counter an opponent's fighting style after seeing it only once, constantly adapting to become stronger mid-battle to overcome his enemies. As he evolves, his physical parameters skyrocket. In his fully realized monster state, his speed is such that top-tier S-Class heroes like Flashy Flash and Atomic Samurai cannot perceive his movements, and he can shatter a barrage of meteors with his blows. In his cosmic form, his abilities become astronomical, allowing him to copy techniques perfectly, move at light speeds, unleash Gamma Ray Bursts, and even mimic the power of Saitama's serious punches, demonstrating a mastery over the flow of all energy in the universe.