Shinobu Yuuki is a teenage human from an unnamed village. Petite with short black hair, she often presents a reserved demeanor, initially covering her face with her hood when approached. After moving to New Tokyo, she wears a modified maid kimono uniform while working at Fairyland Hall. Her personality blends resilience with vulnerability. Bullied by village children for aspiring to leave and climb the capital's space tower, the Amanomihashira, she initially rejects help, though tears reveal her distress. Meeting Touta Konoe, who shares her dream, causes her to gradually open up. She develops affection for him, calling him "big boss bro" and later "sir," demonstrating loyalty and admiration. Her emotional depth surfaces when she lands on top of Touta after a fall, blushing noticeably from embarrassment. Inspired by a pilot she once knew, Shinobu's primary ambition is to compete in the Neo Olympics' Weeklong Grand Solar Race, a dream fueling her determination to leave the village. She displays practical skills as a mechanic, learned from an unnamed friend, which she uses to repair a motorbike crucial to her early interactions with Touta. Their story begins when Touta intervenes in her bullying, revealing their shared dream. They bond further when Touta attempts to sing, his voice sounding "angelic" to Shinobu despite others mocking him. A pivotal moment occurs when a child steals the repaired motorbike, sending Shinobu careening off a cliff. Touta rescues her, and their survival—due to his immortality—cements their mutual respect and a promise to meet at the tower's summit. Shinobu later travels to New Tokyo seeking Touta at the train station and Fairyland Hall. A misunderstanding upon arrival labels her a trespasser, resolved by Touta's intervention. She formally joins the Fairyland Hall staff, integrating into the UQ Holder's environment. Her connection to Touta deepens through a Pactio contract, granting her an artifact: a flying bike. This bond plays a strategic role during the Ba'al Uprising Arc, where she participates in missions alongside UQ Holder members. Following a 47-year timeskip during Touta's confinement as the World Tree, Shinobu's Pactio card turns blank. The epilogue reveals she traveled across planets, eventually settling as a government scientist on a world named "Planet Shinobu." She survives without significant aging until reuniting with Touta. The narrative implies she later dies of natural causes.