Mumen Rider holds the top rank in the Hero Association's C-Class, earning this position through relentless dedication to good deeds regardless of scale. He possesses no superhuman abilities or exceptional combat skills. His defining traits are extraordinary courage and an unwavering resolve to confront any threat, no matter how overwhelming the danger or his own limitations. This profound sense of duty drives him to act, from directing traffic to facing colossal monsters. His appearance features practical, makeshift armor: a brown protective ensemble covering his torso and shoulders, worn over a black leather suit with black gauntlets and knee pads. A green bicycle helmet and dark goggles are his most recognizable gear. Oval spectacles frame his eyes beneath the helmet, complementing his short chestnut-brown hair. He primarily rides a standard utility bicycle nicknamed "Justice," equipped with a front fender light and a handlebar basket. Mumen Rider's personality centers on extreme bravery, loyalty, and honor. He refuses to ignore any crime or retreat from any confrontation, regardless of the opponent's power or near-certain defeat. He maintains acute self-awareness of his physical limitations compared to higher-class heroes and has declined promotion to B-Class for over half a year, believing he lacks the requisite strength. Despite this, he willingly confronts threats designated for A-Class or S-Class heroes to buy time for stronger allies or protect civilians, notably demonstrated during the Deep Sea King incident while other C-Class heroes fled. He holds a passionate belief in justice and exhibits deep respect for those who save him, shown by his sincere gratitude to Saitama after the Deep Sea King battle through a thank-you letter and a meal. He upholds high ethical standards for heroism, firmly believing heroes should not commit dishonorable acts. This conviction led him to defend Saitama's integrity against Charanko's concerns. He displays perceptiveness, recognizing Saitama's true power early on. Furthermore, he occasionally shows sympathy towards villains he perceives as misguided or retaining humanity, such as Garou. In terms of abilities, Mumen Rider relies solely on human physicality augmented by determination. He demonstrates enhanced strength sufficient to harm monsters resistant to gunfire, like Angry Grandpa. His notable endurance and durability allow him to continue fighting after severe injuries from opponents like the Deep Sea King and Garou. He exhibits significant pain suppression, persisting through brutal beatings. His fighting style incorporates hand-to-hand combat and bicycle-based techniques, utilizing moves named "Justice Tackle," "Justice Punch," "Justice Kick," "Justice Crane High Kick," and "Justice Crash" – the latter involving hurling his bicycle as a projectile. A specialized technique, "Riding-Out-of-the-Saddle Mode," enables significantly faster travel by standing while pedaling, though it rapidly depletes his stamina. His most formidable asset is his indomitable willpower, enabling him to face hopeless odds without surrender. Key narrative moments define his character. His debut involved confronting the Paradisers led by Hammerhead, resulting in a severe beating before Speed-o'-Sound Sonic intervened; bystanders mistakenly credited him with the victory. His defining moment occurred against the Deep Sea King at a civilian shelter. Arriving after the monster had defeated other heroes including Genos, Mumen Rider stood alone against the transformed threat to protect refugees. He endured a savage beating, repeatedly rising to attack despite injuries using Justice Tackle and other moves until Saitama arrived, earning widespread respect. Later, while hospitalized from injuries inflicted by Garou, he joined the defense against invading monsters. Trivia notes include his hobbies: DIY shops, bicycles, motorcycles, watching tokusatsu, and reading bike magazines. His primary dislike is bicycle thieves. His name is a play on "kamen" (referencing Kamen Rider) and "mumenkyo" (meaning "unlicensed"), reflecting his lack of a motorcycle license due to repeated traffic violations committed while rushing to crime scenes. He ranks 5th in the series' character popularity poll and conducts patrols during Christmas time. Thematically, Mumen Rider acts as a foil to Saitama. While Saitama possesses immeasurable strength but lacks enthusiasm for heroism, Mumen Rider embodies immense drive and willpower despite physical limitations. He represents the core ideals of heroism—self-sacrifice, unwavering commitment to protecting others, and performing necessary duties regardless of recognition or personal cost, contrasting with heroes motivated by rank, fame, or personal goals. His actions emphasize that heroism stems from small, consistent acts of courage and duty.