Eijiro Kirishima, alias Red Riot, trains as a U.A. High student aspiring to Pro Hero status. Hailing from Chiba Prefecture, his Hardening Quirk lets him solidify and sharpen body parts for defense or offense, first surfacing at age three when he accidentally scarred his eye. Initially self-conscious about his Quirk’s straightforward nature, he found inspiration in Crimson Riot’s philosophy of fearless bravery and chivalry. A pivotal middle school incident—where hesitation left him overshadowed by Mina Ashido’s decisive heroism against bullies—intensified his insecurities. Discovering a Crimson Riot interview advocating courage amid fear sparked his transformation: he dyed his hair crimson, adopted a spiked hairstyle embodying his vow to live without regret, and aced the U.A. entrance exam with the second-highest combined combat-rescue score. With a muscular build, crimson eyes, and jagged teeth, his hero costume features gear-shaped shoulder pads, a fang-like jaw guard, and a belt emblazoned with a red "R." Later upgrades added protective sleeves for safer civilian rescues. Exuberant and fiercely loyal, he champions ideals of "manliness" as bravery, selflessness, and integrity, forging bonds with peers like Katsuki Bakugo, whose relentless drive he admires, and Mina Ashido, whose past heroism spurred his own resolve. His Quirk evolved through relentless training, overcoming early vulnerabilities to heat and stamina depletion. Mastered techniques include Red Counter, a retaliatory defense strike, and Red Riot Unbreakable, a peak-hardening state lasting 30-40 seconds under extreme strain. During internships, he weathered enhanced villains like Kendo Rappa alongside Fat Gum, leveraging Hardening’s regenerative capacity to reinforce damaged areas mid-battle—though prolonged use risks collapse. Relationships underscore his growth: collaborating with Tetsutetsu Tetsutetsu, whose Steel Quirk initially fueled his insecurities before mutual respect emerged, and spearheading critical missions such as Bakugo’s rescue from the League of Villains and the Shie Hassaikai Raid. Post-graduation, he ranked No. 12 among Pro Heroes, apprenticing under Fat Gum before establishing his own legacy. Kirishima’s journey from self-doubt to unyielding resolve crystallized through Crimson Riot’s ethos and battles like confronting Gigantomachia to shield allies. By series’ end, he embodies chivalrous strength, balancing combat prowess with empathy while galvanizing others through unwavering tenacity.