Hayato Furinji, renowned as "The Elder" or "The Invincible Superman," serves as headmaster of Ryozanpaku Dojo and anchors the series narrative. His legendary past features feats like defeating 500 martial artists single-handedly in his youth and undertaking missions against the Yami organization during World War II alongside Mikumo Kushinada. He is the father of Saiga Furinji and grandfather of Miu Furinji, whom he raised after Saiga abandoned her and her mother perished in a snowstorm, an event that deeply forged his protective instincts toward Miu. Leading Ryozanpaku, Hayato champions the Katsujin-ken ("Life-Giving Fist") philosophy, prioritizing life protection over lethal force. He personally trains disciples, including Kenichi Shirahama, affectionately nicknamed "Ken-chan." Despite subjecting Kenichi to brutal regimens, Hayato holds genuine fondness for him, valuing Kenichi's moral compass and resolve. He approves of Kenichi's relationship with Miu but imposes a strict condition for marriage: Kenichi must defeat him in combat—a direct reflection of his fierce protectiveness. This dynamic escalates comically into jealous outbursts after witnessing Miu kiss Kenichi. Hayato's personality merges wisdom with reckless exuberance. Though mellowed by age, he retains boastful tendencies, often distilling complex strategies into blunt declarations like "The fight until you're the last one standing plan." He spends dojo funds irresponsibly and adopts the thinly veiled alter ego "Garyu X," using a robotic mask to pose as a 20-year-old disciple. While convinced of the disguise's success, others perceive it as eccentricity. His powerful sense of justice drives him to intervene globally to shield the innocent, and he demonstrates profound mercy, notably sparing a young fox during survival training and rejecting violence against children. His martial prowess stands virtually unrivaled, earning him recognition as one of the planet's two strongest fighters. Capabilities include suppressing his power to 0.0001% of its full capacity to prevent lethal outcomes, though this diminishes his compassion during combat. He commands 108 legendary techniques, including the defensive Seikūken (creating an impenetrable barrier) and its advanced form, Ryūsei Seikūken (predicting and countering attacks by reading an opponent's "flow"). Additional feats encompass running on water, healing with ki, splitting his vocal cords to speak two sentences simultaneously, and manipulating his anatomy for inhuman flexibility. Physical demonstrations—bending battleship cannons, upending tanks, and moving faster than high-speed cameras capture—solidify his "superhuman" reputation. Key story arcs showcase his development. During the D of D Tournament, disguised as Garyu X, he mentors Kenichi and Miu while blinded, using only 0.0002% of his power to safeguard them. In the Okinawa Arc, he confronts a military base single-handedly, an event likened to "the start of World War III." When Jenazad—a former friend turned Yami master—kidnaps Miu, Hayato blames himself and launches a desperate global search. His relief upon her rescue is palpable; he tearfully thanks Kenichi for protecting her. Later, he neutralizes Jenazad's brainwashing of Miu and collaborates with Kensei Ma for her recovery. Hayato's history with allies and enemies further defines him. His friendship-turned-rivalry with Jenazad involved exchanging medical knowledge before their unresolved battle. He also intervened in the life of Tsutomu Tanaka, facilitating his marriage to Mayu Midou, though he could not prevent their later deaths by Isshinsai Ogata. Enduring loyalty to his late wife manifests through annual grave visits and his rejection of Mikumo Kushinada's romantic advances.