TV-Series
Description
Zenitsu Agatsuma, originating from an urban environment, faced early adversity crushed by overwhelming debt imposed by a swindler. His rescue came from Jigoro Kuwajima, a former Thunder Hashira, who settled the debt in exchange for Zenitsu becoming his disciple. Training under Jigoro in Thunder Breathing was marked by Zenitsu's intense fear and self-doubt, driving him to repeatedly bolt. A pivotal incident occurred during a panic attack: hiding in a tree, he was struck by lightning, permanently altering his hair from black to bright yellow with orange tips. Despite mastering only the First Form, Thunderclap and Flash, Zenitsu developed a fraught rivalry with fellow disciple Kaigaku, who resented sharing their master. Carrying Jigoro's legacy forward, Zenitsu joined the Demon Slayer Corps after his mentor's death.

Zenitsu exhibits extreme cowardice, chronic anxiety, and crippling self-doubt, frequently erupting in loud panic, desperate attempts to flee danger, and declarations of his impending demise. This starkly contrasts with profound courage displayed when protecting others, especially women or comrades. Fearing a lonely death fuels his persistent, often unwelcome, desire to marry. Yet, underlying respect for women surfaces, like demanding Upper Rank demon Daki apologize for harming a civilian. His urban roots grant greater familiarity with elements like trains compared to rural-raised companions Tanjiro Kamado and Inosuke Hashibira. Upon first meeting Nezuko Kamado, Zenitsu developed intense romantic feelings, driving protective instincts. Despite outward frailty, an indomitable will emerges in critical battles. His exceptional hearing detects subtle sounds, discerning emotional states or demonic presence.

During the Entertainment District Arc, Zenitsu joined Tengen Uzui, Tanjiro, and Inosuke on an undercover mission to locate missing wives and investigate demons. Disguised as the female attendant "Zenko" in Tokito House brothel, his heightened hearing detected unusual sounds. Investigation exposed the courtesan Warabihime as a demon, leading to confrontation. Initially overpowered and trapped under rubble, he activated Thunderclap and Flash: Godspeed—moving faster than perception—to escape and later blitz Daki. In the joint battle against Upper Rank Six siblings, Zenitsu demonstrated tactical intellect by correctly identifying the necessity of simultaneously decapitating Daki and Gyutaro, countering Inosuke's mistaken assessment. The fight inflicted severe injuries, including broken feet and multiple slashes, yet endurance and willpower sustained his combat effectiveness.

Character development progressed significantly beyond this arc. Confronting Kaigaku—now Upper Rank Six after becoming a demon and killing Jigoro—Zenitsu battled awake for the first time, channeling rage over his mentor's death. He unveiled the self-created Seventh Form: Flaming Thunder God, visualizing fiery lightning to decapitate Kaigaku. In the final clash against Muzan Kibutsuji, Zenitsu pushed past previous limits, repeatedly using Godspeed despite prior once-daily constraints to land attacks on the Demon King while weakened. Post-series, he married Nezuko, with their descendants appearing in a modern-day epilogue. His mastery evolved from relying solely on Thunderclap and Flash while unconscious to consciously developing new techniques and fighting awake, reflecting growth from debilitating fear to focused resolve.

His abilities center on Thunder Breathing, primarily the First Form: Thunderclap and Flash, involving lightning-fast dashes and slashes. Training refined this into multi-strike variations and Godspeed for imperceptible movement. The self-developed Seventh Form: Flaming Thunder God combines fiery and lightning motifs for enhanced power. Physical capabilities include immense leg strength for high jumps, speed exceeding Upper Rank reactions, and endurance to fight through severe injuries like poison-induced shrinkage or broken limbs. Superhuman hearing grants environmental awareness during unconscious combat and the ability to discern threats or emotions through sound. Extreme terror triggers a "sleeping state," suppressing anxiety to unlock calm precision and full combat potential, though later arcs show diminished reliance on this mechanism.