Nikaido runs the Hungry Bug restaurant in the dystopian Hole, specializing in gyoza favored by her close ally Kaiman. She aids his hunts for magic users experimenting on humans as he seeks the culprit behind his reptilian head and amnesia. Though appearing human, she conceals her own magic-user nature for much of her story. Her long blonde hair and blue eyes frame an athletic build that intensifies after devil transformation. Clothing evolves from dark baggy pants and a Chinese-design black jacket to green overalls with combat boots and leather gloves. Later, a red jumpsuit marks her partnership with En. Post-injury, she dons minimal bandaged attire—a black jacket and panties. Devil training brings heavy black armor, then practical shoulder/leg guards with a hoodie and apron. After recovery, she returns to modest green overalls over a white tank top. Nikaido displays an easygoing, friendly exterior while internalizing anxieties, confident in her physical resilience even during terror. Devil form amplifies this into unnatural cheerfulness and constant smiling amid danger. She remains fiercely loyal and protective toward Kaiman and allies. Combat revolves around exceptional martial prowess, defeating foes like Hole-kun unarmed and moving at remarkable speeds. As a restaurateur, she possesses advanced cooking skills. Her magic manipulates time via a metallic box with a revolver-like cylinder holding five crystalline "bullets." Firing one transports her and touched individuals backward in time, allowing alterations that reconcile upon return. Expending all bullets destroys the box permanently. Devil form grants heightened strength, speed, motivation, and dark vision but depletes magic reserves, reverting her to baseline. Born in the magic realm, orphaned Nikaido was raised by an elderly couple alongside adoptive siblings Yakumo and Kawajiri. Martial arts training surpassed typical sorcerer skills. Early magic experiments accidentally birthed her time device, causing Yakumo’s death through past alterations. Repeated attempts to fix this fractured her family until Kawajiri—now near-devil Asu—rescued her. Asu guided her relocation to the Hole to avoid further magic. While establishing herself there, Nikaido defended restaurant owner Syueron from magic-user victims, joining his business as bodyguard and gyoza vendor. After vandalism destroyed the shop, Syueron departed for the magic realm, leaving her to rebuild as the Hungry Bug. Volunteering in body recovery, she discovered Kaiman’s decapitated reptilian-headed form. Nursing him to health forged their partnership, with her pledging to restore his original body. Key events include battles against magic users like Fujita and Noi—the latter admiring her combat skills. She joined a zombie extermination event for a restaurant meat grinder and entered a debt-settling boxing tournament, leading to imprisonment and Kaiman’s rescue. A near-fatal encounter with En’s enforcers Shin and Noi forced escape via magic door to a hospital. Traveling to the magic realm with Kaiman exposed Nikaido’s hidden magic, attracting En’s attention. Captured and tortured, she became his forced partner. During captivity, Asu/Kawajiri subjected her to devil training, where impractical armor mimicked devil physiology, triggering partial physical transformation that altered her personality and physique until magic depletion reverted her. Post-recovery, she aided Kaiman against Cross-Eyes leader Hole-kun, helping resolve the conflict. Her arc concludes with the Hungry Bug’s reopening alongside Kaiman, reflecting her journey from trauma-shadowed magic user to resilient restaurateur balancing past abilities with commitment to found family.