TV-Series
Description
Ōyama appears in the anime Zero-sen Hayato as a supporting character with the rank of first-class flight petty officer in the Imperial Japanese Navy, a rank equivalent to petty officer first class. He is one of the experienced pilots selected for the elite aerial unit known as the Bakufū-tai, which is assembled under the command of Captain Miyamoto, and he serves alongside the young ace Hayato Azuma. Physically, Ōyama is described as stout and heavy-set, a build that contrasts visibly with that of his frequent flying partner Hosokawa, who is slender, and the two men are often presented as a contrasting but well-matched pair within the squadron.

In combat, Ōyama is most notable for his participation in a three-aircraft formation with Hayato and Hosokawa that carries out the mijinkuzushi sankaku-zeme, a coordinated simultaneous attack devised by Hayato after watching seagulls in flight. Ōyama and Hosokawa perform this maneuver with tightly synchronized teamwork, which shows that Ōyama is a disciplined and reliable wingman capable of executing the protagonist's tactical ideas effectively. His role in the story is therefore largely that of a loyal and steady comrade within the Bakufū-tai, contributing to the unit's successes through dependable formation flying and cooperation rather than through individual feats of heroism.

On a personal level, Ōyama forms a romantic attachment to O-hana, one of the nurses stationed at the base on Morotai, and the two are depicted as a warm and devoted couple. This relationship gives him a personal stake in the war beyond the cockpit and adds a more human dimension to his military service in the southern theater. The available information about his background and inner life is limited, and he does not undergo a major personal transformation over the course of the story; his development is expressed mainly through his steady bonds with his fellow pilots and the quiet sincerity of his personal connection with O-hana. Overall, Ōyama stands out as a dependable supporting figure defined by his solid physical presence, his effective teamwork with Hosokawa, and his gentle relationship with the nurse he cares for.