Discovered unconscious on a beach by Team Hitotsuyanagi during an investigation, Yuri Hitotsuyanagi displayed a naive, childlike, and bubbly personality, often appearing lively and energetic. Her origins stemmed from a classified Gehenna experiment to create a fully artificial Lily. This artificial nature granted her the unique ability to copy and utilize multiple rare skills, unlike natural Lilies who typically possess only one innate rare skill. She was accidentally released from a Gehenna transport ship during a storm surge prior to her discovery.

After her rescue, Team Hitotsuyanagi cared for and trained her at Yurigaoka Academy, where she forged strong bonds, particularly with Riri Hitotsuyanagi and Yuyu Shirai. Concerns arose about her potential danger to humanity due to her creation within a Huge and her artificial nature, prompting government capture attempts. Team Hitotsuyanagi intervened to protect her from these efforts.

Her story culminated during a Huge attack, where she sacrificed herself to destroy an oncoming Huge, seemingly dying to ensure her friends' safety. However, unknown to the team, she survived this sacrifice and was later washed ashore, unconscious, on a distant island. Her surname "Hitotsuyanagi" means "one willow," sharing the family name with Riri Hitotsuyanagi. The characters in her given name mean "tie, bind" (結) and "pear" (梨).