Hitoka Yachi, a first-year Karasuno High student, becomes the boys' volleyball team's replacement manager after senior manager Kiyoko Shimizu recruits her. Though initially hesitant due to her lack of volleyball knowledge and club experience, she agrees when Kiyoko approaches her. Her graphic designer mother cautions against half-hearted commitment, prompting Yachi to reconsider. Witnessing the team's intense dedication solidifies her resolve; she firmly declares her intention to manage, earning her mother's proud approval. Petite with blonde hair slightly past her chin and light brown eyes, Yachi often wears colorful star-shaped hair accessories, leading multiple characters to note her cute appearance. Post-timeskip, her hair is slightly longer and usually tied in a ponytail. Prone to pronounced anxiety and an overactive imagination, Yachi frequently misjudges others. She initially mistakes Shoyo Hinata for a manager due to his height and fears Coach Ukai is a threatening delinquent, later apologizing for both assumptions. Easily flustered, she covers her eyes during team uniform changes. She develops strategies to manage her nervousness, like openly acknowledging her anxiety—advice she shares with Tadashi Yamaguchi. Despite underestimating her value, others recognize her organizational skills, empathy, and encouragement. Her meticulous note-taking, influenced by her mother's design work, leads her to tutor Hinata and Tobio Kageyama after their academic failures. Her managerial journey deepens upon overhearing the team's funding shortage for a Tokyo training camp. Utilizing her design skills, she creates a promotional poster featuring Hinata, assisted by her mother and players. The successful fundraiser secures the trip expenses and officially solidifies her role. At the camp, she supports Kageyama's solo practice by tossing balls and observes team dynamics. She notably mediates tensions between Hinata and Kageyama after their argument over the "quick attack," facilitating communication about their mutual trust to help them reconcile. During tournaments, Yachi's confidence visibly grows. She cheers enthusiastically, analyzes plays (noting opponent tactics), and corrects spectators' misconceptions. Her observational skills aid the team, such as advising Kageyama on a less conspicuous disguise for scouting rivals. She bonds closely with Kiyoko, who protects her from rowdy opponents and stray balls. When Kiyoko mentions the third years' impending graduation, Yachi becomes emotional but masks it. Key relationships drive her development: - **Kiyoko Shimizu**: Acts as her mentor and protector; their interactions help Yachi integrate into the team. - **Shoyo Hinata**: Encourages her self-worth and accompanies her to confront her mother. They share a supportive friendship, and she actively mends his rift with Kageyama. - **Tobio Kageyama**: She assists his training, celebrates his successes, and offers practical advice. Their camaraderie is evident during his disguise attempt. - **Tadashi Yamaguchi**: They relate through shared nervousness; she comforts him before matches and later develops a close personal relationship post-timeskip. Post-timeskip, Yachi attends college and interns at a Tokyo advertising design company, aligning with her inherited design aptitude.