Hikari is one of the older Haibane residing at Old Home, having lived there for approximately four years, which makes her the third most senior after Reki and Nemu. Her given name means Light, which she received from the dream she experienced inside her cocoon, a dream in which she was surrounded by a sparkling light. She has a youthful and feminine appearance, with blonde or light yellow hair worn at shoulder length, purple eyes, and she typically wears glasses along with a ribbon in her hair.

In terms of personality, Hikari is fundamentally a kind and caring individual who is genuinely concerned for the well-being of the other Haibane at Old Home. She is often the first person to volunteer when help is needed, demonstrating a proactive and helpful nature. However, she also has a somewhat ditzy and scatterbrained side, frequently acting before thinking things through or forgetting to mention important information to others. A notable example is her failure to inform the newly born Rakka that Haibane are not permitted to speak inside the temple, leaving Rakka confused in a situation that required silence. Despite this forgetfulness, Hikari possesses a good deal of knowledge about Haibane customs and the rules they must follow, even if she does not always remember to share it at the right time. She also has a mischievous streak, shown when she uses a sacred mold for a purpose other than its intended one, finding humor in situations that others might take more seriously.

Hikari plays a significant role in the daily life of Old Home and in the story through her actions and relationships. One of her most notable acts is volunteering to be the Halo Bearer when the new Haibane Rakka is born. Her motivation for this role, however, is not entirely selfless; she wishes to borrow the special mold used to create the halos so that her coworkers at the bakery can experiment with it, hoping to create halo-shaped pastries. This decision has unintended consequences, as the mold's stickiness transfers to Rakka's new halo, causing it to generate excessive static electricity that makes Rakka's hair stand on end and gives her a faint aroma of baked goods. Hikari is deeply conscientious about her actions, and when she realizes the trouble she has caused for Rakka, she feels genuinely guilty and responsible.

Her daily life involves working at the oldest bakery in the center of the town of Glie, where her duties include tending the cash register and stocking fresh products on the shelves. Her coworkers value her contributions, insisting that she does more than her share of the work, which is why they do not mind when her friends from Old Home stop by to visit and enjoy some treats. Her key relationships are with the other Haibane of Old Home. While she gets along with everyone and is part of the close-knit group, her dynamic with the more practical and tomboyish Kana has an element of sibling-like friction, with the two occasionally picking at each other despite an underlying fondness. She is also shown to have a caring relationship with the Young Feathers, the youngest Haibane children at Old Home, as she is capable of stepping in to look after them when Reki, their primary caretaker, needs a day off.

Throughout the story, Hikari experiences subtle but noticeable development. When Rakka falls into a deep depression, Hikari becomes very hard on herself, convinced that she is not doing enough to help and briefly resents Reki for being secretive about Rakka's condition. This shows her deep emotional investment in her friends and her tendency to internalize blame when things go wrong. These moments reveal a resilience and an ability to take on responsibility when it truly matters, moving beyond her typical scatterbrained exterior. Hikari does not possess any supernatural combat abilities, but her notable skills include her baking and customer service talents from her job, as well as her practical knowledge of Haibane laws and traditions, which makes her a valuable source of information for the group, provided she remembers to share it.