Shiina Yuya is a bounty hunter driven by the pursuit of the largest bounty, which stands at 1,000,000 ryo for the capture of Demon Eyes Kyo. She initially follows Kyoshiro, bonding with him until Kyo reawakens and takes over. Once Kyo fully emerges, she shifts her allegiance to him, gradually developing trust and faith in his abilities despite his often abrasive demeanor. In Aokigahara Forest, she discovers that Kyoshiro was responsible for her older brother's death and resolves to confront him when he resurfaces. Yuya remains intrigued by both Kyo and Kyoshiro, harboring a deep-seated secret about the Mibu Clan that her brother Nozomu shared with her during her childhood. The Aka no Ou suspects she might be a seer, though this remains unconfirmed. In Chapter 229, while speaking to her brother, she openly admits her love for Kyo in front of everyone, declaring she would never forgive him if he harmed Kyo.
Though Yuya can be temperamental and even violent when provoked, she possesses a kind and gentle nature at heart. Both Benitora and Akira develop crushes on her, and many other characters come to cherish her company, considering her a dear friend worth protecting. By the end of the manga, Yuya is searching for Kyo, and in a bonus chapter, it is revealed that they eventually live together.
