Saitama, a bald man of average height and lean athletic build, owes his hairless appearance to an extreme three-year training routine. Once an unemployed salaryman, his life shifted upon impulsively rescuing a child from Crablante—an act that spurred the child’s grandfather to found the Hero Association. Determined to become a hero, Saitama adopted a daily regimen of 100 push-ups, 100 sit-ups, 100 squats, and a 10 km run, coupled with a basic diet and rejection of climate comforts to fortify mental discipline. This grueling routine unlocked exponential physical growth, granting near-unmatched power at the cost of his hair. His demeanor oscillates between apathy and dry humor, his boredom stemming from a lack of worthy adversaries. Battles often conclude anticlimactically with a single punch, yet he upholds steadfast principles, valuing altruism over acclaim. He anonymously cedes credit to peers—evident when he let others claim victory over Deep Sea King—and rejects leveraging his power for personal benefit. Minor irritations, such as missed bargains or mocking his baldness, provoke sharper reactions than world-ending threats. Saitama’s capabilities defy natural laws, his strength, speed, and durability rendering him virtually indestructible. His power escalates endlessly, as seen when emotional intensity during his clash with Garou accelerated his growth beyond quantifiable metrics. Notable feats include neutralizing Boros’s planet-leveling strike with a "serious punch" and unwittingly reversing a dystopian future by countering Garou’s cosmic onslaught. Ranked low in the Hero Association due to mediocre exam scores, he climbed to A-Class Rank 39 despite public skepticism that dismissed his triumphs as luck or misattributed them to higher-ranked heroes like King. After his Z-City home was destroyed during the Monster Association conflict, he relocated to A-City’s headquarters. He later co-founded the Hero Name Victim Association to protest titles like "Caped Baldy," critiquing the organization’s focus on image over substance. Interactions reveal contradictions: he mentors Genos, a vengeance-driven cyborg, yet remains indifferent to his tragic past; allies with Mumen Rider and Bang, offering tactical guidance or quiet empathy; and humorously thwarts Speed-o’-Sound Sonic’s rivalry through effortless superiority. Central to his narrative is a pervasive existential ennui, a longing for challenges that might reignite his fervor for heroism. This internal struggle contrasts his unyielding dedication to protecting others, even without recognition. His story weaves mundane frustrations with unparalleled might, framing a hero who embodies paradoxical humility—a man redefining strength through simplicity.