Hikari is a young girl who was sent to Kokoro Library to train as a special-case librarian while her mother was in hospital. At first she appears introverted and refuses to speak or do any work. At one point she even lashes out at Kokoro for looking at a photograph of her mother. After attempting to run away from the library, Hikari opens up to Kokoro and the two become close friends. Once her true personality is revealed, Hikari appear strong-minded, honest and affectionate. Though she is even younger than Kokoro, she seems wise beyond her years as she tells Uezawa to give up on Iina as their 'love will not bloom.' She also criticises Aruto's novels for their lack of realism (though she later admits that she quite enjoys them). Hikari has green eyes and wears a single side pigtail in her otherwise loose dark hair. Her uniform is pink.