Inko no Tsubasa, known as Tsubasa, was once a parakeet cared for by Gorō Mutsumi. A wing injury led Gorō to nurse her, forging a deep bond. After seeming to recover, she tried to show her gratitude by flying but fell from a window due to her unhealed wing, resulting in her death. This traumatic end left her with a profound fear of heights that carried into her next life. Her name, meaning "wing," reflects this past existence and defining trauma.

Reincarnated as one of Gorō's twelve guardian angels, Tsubasa manifests as a young woman blending tomboyish energy with femininity. Her hairstyle resembles parakeet wings, and she is consistently associated with the color red. Starting as an Intermediate-ranked angel, her significant dedication to improving her abilities and protecting Gorō results in a promotion to Senior rank in the second season.

Profound affection and devotion for Gorō drive Tsubasa. This loyalty fuels her animosity towards Rei, the Red Phoenix (Suzaku), who harbors romantic feelings for her but harmed Gorō. Her personal journey involves diligently working to overcome her acrophobia, stemming directly from her fatal fall, to become stronger in her duties.

Within the group of twelve angels, she functions as a dedicated member focused on supporting Gorō and collaborating with her sister guardians. Her development emphasizes perseverance against fear and striving for self-improvement. In the second season, she works as a newspaper deliverer after finishing school, frequently using a bicycle for her commute and leisure.