Hiroyuki Fujita is the central male protagonist of the To Heart series, particularly in To Heart: Remember My Memories. He is a high school student who often presents a dry, sarcastic, and aloof exterior, which can make him appear indifferent or perpetually sleepy and difficult to motivate. This tendency to doze off is so pronounced that his childhood friend, Akari Kamigishi, has the daily ritual of waking him up for school. Despite his lazy façade, Hiroyuki possesses a kind heart and a strong sense of empathy, although he typically demonstrates these qualities through his actions rather than his words. He has a habit of becoming involved in other people's problems once he is concerned about them, which reveals a protective side to his personality. Hiroyuki is also notably dense when it comes to recognizing romantic cues and feelings directed towards him, a trait that frequently leads to misunderstandings and unintentionally selfish behavior. Physically, he is described as fairly tall and good-looking with a slim build, short dark brown hair with spiky bangs, and brown eyes.

A core aspect of Hiroyuki's background is his deep, longstanding friendship with Akari Kamigishi, which has existed since their time in kindergarten. They are also close with their mutual friend Masashi Sato. In To Heart: Remember My Memories, Hiroyuki's central role revolves around the return of Multi, an experimental android whose memory of her previous time with the group has been erased. He becomes intensely focused on helping Multi restore her lost memories, believing that sharing the same experiences they had before can rebuild what she has lost. This preoccupation drives the main emotional conflict of the story, as his determined efforts to help Multi inadvertently cause strain in his relationship with Akari, who grows jealous and depressed over his diverted attention. His character development in this sequel is marked by him becoming more visibly anguished and vocal about his emotional investment, a stark divergence from his typically reserved nature.

Hiroyuki's key relationships create a complex web of romantic tension. Aside from his central dynamic with Akari, his childhood friend Lemmy Miyauchi confesses her long-held feelings for him and asks him to move with her to America, a request he ultimately declines. Furthermore, their friend Kotone Himekawa also admits her love for him. Meanwhile, the friend group dynamic is further fractured when Masashi Sato confesses his own feelings to Akari. Throughout these conflicts, Hiroyuki gradually matures in his ability to understand and express his emotions, ultimately navigating the turmoil to solidify his mutual bond with Akari by the series' conclusion. A notable example of his lingering obliviousness occurs even after this resolution, as he still requires Akari to wake him up, and a later attempt by her to rouse him for an occasion results in a comical mishap. Another notable ability or trait is that he is implied to be "Brilliant, but Lazy," possessing untapped potential in academics and athletics that he rarely chooses to exercise due to his perpetual lack of motivation.