TV-Series
Description
Hiyono Yuizaki is the heroine of the story and a second-year student at Tsukiomi Academy, where she serves as the president and sole member of the school's newspaper club. Her appearance is youthful and petite, with brown hair typically tied in low twin braids and long bangs that frame her brown eyes. Despite being one year older than the protagonist, Ayumu Narumi, her energetic demeanor and small stature often make her seem younger than she is.

On the surface, Hiyono presents herself as an inquisitive, bubbly, and relentless chatterbox who is always cheerful and eager to involve herself in any exciting event that occurs around Ayumu. She is bold, confident to the point of overconfidence, and completely unashamed of her more questionable methods. She openly uses blackmail to extract information from police officers and other individuals, carries weapons such as a taser for self-defense, and takes pride in skills like lock-picking and planting tracking devices on unsuspecting targets. Her reputation at school is such that even teachers are rumored to be vulnerable to her information-gathering network, and many students prefer to avoid becoming her enemy.

However, this over-the-top personality is largely a constructed role. The true Hiyono Yuizaki is a highly trained adult spy, estimated to be around twenty years old or older during the main events of the story. She was assigned by Ayumu's missing older brother, Kiyotaka, to enroll at Tsukiomi Academy two years prior to the main storyline, pass the entrance exams, and build her reputation as a nosy journalist in order to have a plausible reason to insert herself into Ayumu's life. Her mission was to act as a supporter for Ayumu, pushing him forward in his investigation into the Blade Children and helping him develop the confidence to rely on others, despite his naturally antisocial and introverted tendencies. While her extroverted and meddlesome nature is an act, many of her actions, such as her fierce loyalty and her words of encouragement for Ayumu, are genuine expressions of her own will rather than simply following orders.

Hiyono's primary motivation throughout the series is to support Ayumu. As a reporter and an investigator, she is driven by an intense curiosity and finds excitement rather than fear in dangerous, life-threatening situations. She wholeheartedly believes in Ayumu's deductive abilities and acts as his self-appointed sidekick, keeping him moving forward even when he is reluctant or in despair. Her role in the story is that of a valuable information asset; she gathers critical data, hacks into databases, and uses her network of blackmailed contacts to aid in solving the various cases that connect to the mystery of the Blade Children. There are numerous instances across both the anime and manga that imply she has romantic feelings for Ayumu, and he eventually shows a reciprocal level of care and trust for her.

Her key relationships center almost entirely on Ayumu Narumi. She is constantly by his side, acting as his polar opposite in terms of sociability but serving as the engine that drives him into action. Her relationship with Kiyotaka Narumi, Ayumu's older brother, is the foundation of her involvement, though she is shown to harbor a personal bitterness and hatred toward him for the suffering and certain death he has forced Ayumu to face. In the manga, the depth of her commitment is fully revealed when her status as a spy is exposed, yet her bond with Ayumu remains strong. At the conclusion of the story, Ayumu gives her one of his earrings, a symbolic gesture that represents their connection, and she is later shown visiting him in the hospital.

Regarding her abilities, Hiyono possesses no supernatural powers but is exceptionally talented in espionage and information gathering. She has top-notch acting skills, allowing her to seamlessly maintain a false persona. She is a skilled hacker and computer user who can access numerous databases, and she is proficient in lock-picking, surveillance techniques such as planting bugs and trackers, and even hand-to-hand combat and firearms training that allow her to keep up with dangerous individuals. She also demonstrates fluency in foreign languages, including German, which aligns with her background as an intelligence agent.
Cast