Eijirō Kirishima, a U.A. High School student, once grappled with self-doubt after freezing during a middle school crisis. This shame fueled his admiration for Crimson Riot, a vintage hero whose emphasis on valor reshaped Kirishima’s identity. Embracing crimson spiked hair as a pledge to embody unyielding courage, he forged a new path. His Quirk, Hardening, grants rock-like skin for formidable defense, its potency tied to his mental resolve. Through disciplined training, he mastered techniques like Red Counter—a retaliatory strike after absorbing blows—and Unbreakable, a peak-defense state lasting 30–40 seconds. Though initially dismissing his ability as mundane against flashier Quirks, Kirishima’s tenacity refined it into a shield capable of weathering bullets, explosions, and brutal onslaughts. Kirishima champions "manliness" as a creed of fearless loyalty, often tearfully praising heroic acts. His gregariousness bridges friendships with explosive-tempered Katsuki Bakugo, whom he views as an equal, and Mina Ashido, whose past bravery once underscored his insecurities. This devotion drives him to defy orders when allies are threatened, exemplified by his pivotal role in rescuing Bakugo from the League of Villains. Interning under Pro Hero Fat Gum, Kirishima clashed with Kendo Rappa, a brawler whose relentless assault tested his resolve. Drawing on Crimson Riot’s teachings, he pushed past despair to shield others, even as his body faltered. Such feats during joint missions earned respect from mentors and peers, marking him as a steadfast protector. Ranked No. 12 among Pro Heroes post-graduation, Kirishima retains his crimson spikes and Oni-themed gear. His growth—from insecurity to unshakable resolve—mirrors his relentless pursuit of strength and integrity. Bonds like his rivalry-fueled camaraderie with Tetsutetsu Tetsutetsu and his dynamic within the Bakusquad highlight his knack for uplifting others through sheer authenticity and grit.