Chika Watanabe, known professionally as Yūhi Yūgure, is a high school student whose quiet and reserved demeanor creates an aloof, unapproachable aura, leading classmates to perceive her as a loner. This contrasts with her persona as a voice actress, a career she entered with the personal motivation of reaching her father, who left her family when she was young. Her mother strongly disapproves of this path and has threatened to make her quit.

Despite her off-air reserve, she is a dedicated and passionate voice actor, recognized for her professionalism during recordings. She co-hosts a radio program set in a high school atmosphere, a premise supported by both hosts ostensibly attending the same school. Her relationship with her co-host, Yumiko Sato, is initially adversarial, marked by constant bickering and hostility off air, starkly opposed to their friendly on-air dynamic.

Their relationship evolves through shared experiences, including fulfilling radio promises like visiting a butcher shop to try croquettes and attending a sleepover. When a stalker incident leads a male student to reveal private details of her life without consent, she punches him in class, condemning his actions. Yumiko Sato publicly defends her by making a video demanding fan support. In response, she reveals that the director of their radio show is her father, leading them to drop their professional personas and continue the show more authentically.

She supports Yumiko when Yumiko lands an antagonist role in *Illusionary Mecha Soldier Phantom* and struggles with retakes and keeping up with other voice actors. She advises Yumiko to win the mental game against her peers, resulting in Yumiko’s successful performance. By the end of their documented arc, their relationship transforms into a complex bond she defines as an "eternal rivalry," explicitly stating she does not consider Yumiko a friend.