Genji Togashi is the son of Japanese navy pilot Togashi Genzo, a wartime comrade of Edajima Heihachi. After his father's death on Saman Island, Isa Takemitsu took him hostage, threatening his life to coerce Edajima into revealing an atomic bomb. Togashi intervened by throwing a toy airplane at Takemitsu, enabling Edajima to counterattack. Following his mother’s death, his older brother Togashi Genkichi raised him. When Genkichi enrolled at Otokojuku only to be killed months later by Dokugantetsu and Senkuu during the Great Trembling Conquest of the Unified Eight, Togashi swore revenge against Daigouin Jaki, whom he held responsible, leading him to enroll at Otokojuku three years later.

Physically, Togashi bears a prominent scar over his left eye, sports long disheveled black hair, and a pencil mustache. He wears Otokojuku’s standard uniform—rarely buttoned—and a school cap gifted by his late brother, typically accessorized with bandages on his wrists and waist where he conceals a knife. Later, in the spin-off *Sora Yori Takaku*, he adopts a professional appearance with shorter combed-back hair and a suit, though he reverts to his uniform during conflicts like the war against EXP.

Initially portrayed as brave and resilient, Togashi habitually confronts stronger foes, relying on sheer determination to withstand their attacks. His role later shifts toward comedic interactions alongside characters like Toramaru, marked by exaggerated reactions and gullibility—such as being deceived by an elderly woman claiming him as her deceased son. Despite this, his core bravery persists in combat. He prides himself on surviving seemingly fatal situations, declaring that "all the cockroaches on earth will die before he does." His loyalty manifests in actions like raiding a yakuza headquarters to rescue the woman who scammed him and enduring punishments to protect peers—confessing to wearing briefs in the live-action film to shield Hidemaro, resulting in his immersion in a scalding oil bath.

Togashi’s Brawler Killing Style emphasizes street-fighting and knife tactics over formal martial arts, leveraging extreme pain tolerance and mental fortitude. Signature techniques include the White-Tooth Blade-Catcher (halting blades with his teeth), the Ball Crusher (striking an opponent’s testicles), and the suicidal Volunteer Bombing Kill (strapping dynamite to his chest). He also employs combination attacks with Toramaru, like the Boar Leaping Jumping Body Cannon (launching Toramaru via rubber slingshot) and the Great Fart Cannon Human Wheel (a synchronized rolling assault). His resilience enables him to survive Otokojuku’s "specialties," including narrowly avoiding guillotine decapitation and enduring the Human Watermelon Bash (burial in sand while evading sword strikes).

Key narrative arcs include his participation in the Oil Bath trial to disprove cowardice accusations and volunteering for the Slash-a-Mole duel against Maruyama. During the Four Great Trials of Terror, he battled Hien while dangling from a cliff-edge rope in the Dangai Chuurankan, performing the Blood Battle Reinforcement by carving the kanji for "battle" into his chest to motivate Hien. Post-graduation, as depicted in *Sora Yori Takaku*, he serves as Edajima’s secretary. The live-action film highlights his loyalty through his confession about briefs and participation in the condensed Three Great Trials of Terror against the Kanto Gogakuren.