Yayoi Uenoyama is Ritsuka Uenoyama's older sister, living with him and their parents. She possesses long black hair, blue eyes, and stands 163 cm tall, frequently noted for her beauty and strong resemblance to her brother in their shared facial features. A college art student, she also works as a campus model. At home, Yayoi exhibits a candid and unpolished personality, often acting bossy or irritable towards Ritsuka. She enters his room without knocking, throws misplaced belongings at him, and demands he handle chores like cooking dinner when late. Despite this bluntness, she cares deeply for her family, with Ritsuka assisting her during instances of period pain despite his embarrassment. This home behavior contrasts sharply with her polished public image, where she appears elegant and approachable. Yayoi harbored a prolonged, unrequited crush on Akihiko Kaji, her brother's bandmate and college classmate. She frequently sought opportunities to interact with him, asking about band practices or tidying her appearance before greeting him. Her feelings were not reciprocated, leading to a significant moment of heartbreak where she cut her hair, symbolizing her resolve to move on. She later entered a relationship with Koji Yatake, marrying him and having a daughter, as shown in *Given: 10th Mix*. Observing her brother's development, Yayoi comments on his passion for music and relationship with Mafuyu Sato. She notes when Ritsuka becomes intensely focused on guitar practice, comparing it to his younger self, and expresses concern for his well-being. At Given's live performances, she shows surprise at Mafuyu's singing talent and asks Akihiko to support Ritsuka. Her name, Yayoi (弥生), carries meanings related to "spring," "thriving life," or "March" in the traditional lunar calendar. Additional trivia includes her ownership of a pink-colored phone and her blood type being B.