In the context of the anime HEN, which adapts the second series of Hiroya Oku's manga, the character named Hiroya Oku is a fictionalized version of the manga's creator. He appears as a supporting character and the best friend of one of the main protagonists, Yūki Satō.

Physically, this character is depicted as being very short in stature, with a face that is often likened to a doll’s or a figurine's, giving him a somewhat unique and almost childlike appearance. His defining trait within the story is his ambition to become a professional manga artist. This aspiration directly mirrors the real-life path of his creator, who first devised the story of HEN as a young artist.

The character's primary role is to act as a close friend and confidant to Yūki Satō, the androgynous male student who unintentionally becomes the object of his classmate Ichirō Suzuki’s affections. His presence in the narrative offers a grounded perspective on the unusual and ambiguous romantic situation developing between his friend Satō and Suzuki. Being an aspiring creator himself, he may also serve as an observer of the strange, almost story-like events unfolding around him.

As a character who exists as a self-reference by the author, Hiroya Oku does not undergo a significant personal transformation or development arc. His role is more static, serving as a narrative device to advance the plot concerning the central relationship. The character’s main function is as a recurring presence in Satō’s life, supporting his friend and reacting to the increasingly complicated and humorous scenarios typical of the series, which is a romantic comedy. His notable ability is not a physical skill but his knowledge and practical drive related to creating manga, a trait that distinguishes him from the other students and defines his purpose within the story.