Hinata Asaka is a major character who comes from the Human World to study at Sunshine Academy, where she is a classmate of the jewelpet Ruby in the Plum Section. Before the series begins, she had been Ruby's roommate, but after a room shuffle at the start of the school year, she moves in with the jewelpet Peridot and becomes her partner.

Hinata has a shy, timid, and gentle personality. She is notably not good at sports. Despite her reserved nature, she is a supportive friend to her classmates, particularly to Ruby, and is often described as the most rational and understanding member of her group. She is the only person who can understand Ruby well, even if she sometimes finds herself confused by certain situations. A recurring personal habit is her fondness for wearing T-shirts that feature I heart X slogans.

Throughout the story, her close relationships play a key role in her development. Her friendship with Ruby is strong from the beginning, and living with Peridot helps her become more active and confident, gradually coming out of her shell. Her initial aspirations are to become a preschool teacher after college, which reflects her caring and supportive nature. However, in the epilogue set five years later, she has instead chosen to follow in her father's footsteps and become a firefighter.