Hina Kusaka is a character who appears exclusively in the live-action television series Pretty Guardian Sailor Moon. She was created specifically for this adaptation and does not exist in the original manga or anime storylines. Hina is the daughter of Mamoru Chiba's benefactor, a person who provides financial support for Mamoru's education and upbringing. Having grown up alongside him since childhood, she shares a long and deep history with Mamoru, and the two are engaged to be married. As a university student, she is also an aspiring teacher.

In terms of personality, Hina is portrayed as a remarkably kind, generous, and gentle young woman. She is sincere and caring, treating those around her with genuine warmth. When she is introduced, she befriends Usagi Tsukino without any suspicion or jealousy, seemingly unaware of Usagi's deep feelings for Mamoru. Her inherent goodness makes it impossible for even her romantic rival, Usagi, to feel hatred or resentment toward her. Usagi instead finds herself admiring Hina's character.

Despite her poised exterior, Hina is not oblivious to the emotional dynamics at play. She begins to worry that Mamoru does not truly love her, suspecting that his commitment to their engagement stems from a childhood promise and a sense of obligation rather than genuine romantic affection. This insecurity is compounded by Mamoru's growing distance and preoccupation with his duties as Tuxedo Mask and his connection to Usagi.

Hina's primary role in the story is as a catalyst for the romantic development between Usagi and Mamoru, creating a love triangle that forces the central characters to confront their true feelings. Her presence initially devastates Usagi, who feels hopeless and inferior upon seeing how kind Hina is and how happy Mamoru appears with her. However, Hina's role evolves beyond that of a simple obstacle. She becomes a figure of tragic dignity and emotional maturity.

The key relationships in Hina's life are with Mamoru Chiba and Motoki Furuhata. Her relationship with Mamoru is complex; it is built on years of shared history, familial obligation, and a genuine fondness, but it lacks the deeper, passionate love he feels for Usagi. Motoki, a mutual friend, serves as a link between them and is unintentionally the source of a painful revelation when he mentions Mamoru's true feelings without realizing Hina is listening.

Hina's story arc culminates in her decision to end her engagement with Mamoru. After a youma attack makes her realize that Mamoru is truly in love with Usagi, she makes the difficult and selfless choice to break up with him. She tears up her plane ticket for their planned studies in London, telling Mamoru that she knows she is an important person to him, but not the one he truly loves. She walks away hiding her own sadness, wishing him well. After this farewell, her later life is briefly explored in a DVD special. She is shown to have become an actress, working on a television drama titled Phantom Thief Tuxedo Knight. In this role, she finds herself attracted to the actor playing the hero, who strongly resembles Mamoru.

Hina Kusaka is a civilian character and possesses no supernatural powers or abilities. Her significance lies entirely in her emotional strength and her narrative function as a foil to Usagi. The meaning of her name provides a symbolic layer of contrast; the characters used to write her family name and given name both mean sun, which contrasts with Usagi’s name meaning moon and Mamoru’s name meaning earth.