Retto Enjo, a high school student with a slim yet muscular frame and short wavy red hair, channels his unwavering sense of justice into protecting others—especially Kirara Hoshino, his emotionally withdrawn childhood friend. A traumatic encounter years prior, when a Censor Bug exploited Kirara’s H-energy, left her scarred and fractured their bond, driving Retto to join the HxEros team. Armed with a wristband XERO gear, he converts H-energy into combat techniques like the Megaton Punch, though battles often result in accidental nudity due to energy-induced clothing damage.

His abilities come at a cost: absorbing excess H-energy triggers "Beast Mode," a feral state marked by irrational aggression toward women, a ethically fraught tactic his team avoids. Guilt over failing Kirara fuels his resolve to shield others from similar pain, while his relationships with teammates Momoka Momozono, Sora Tenkuji, and Maihime Shirayuki challenge his growth. Momoka’s unspoken affections and Sora’s accidental entanglements contrast his singular focus on reconnecting with Kirara, culminating in their mutual romantic confession and partnership as they confront her trauma and his lingering remorse.

Post-conflict, Retto leads efforts to neutralize remaining Censor Bugs and integrate former foes like Chacha, their princess, into society. His family ties include a younger sister, Hiro, and uncle Jō Anno, commander of the Saitama Earth Defense Force, whose clashing personalities yield tense but collaborative efforts to safeguard humanity. Bonds with his loyal dog Runba and alliances with Tokyo HxEros allies further cement his role as a unifying figure balancing duty, growth, and an expanding web of responsibility.