Masaomi Yamada is a supporting character in the anime Please Teacher!. He works as a teacher at the high school where the main characters attend. He is described as a quiet, reclusive, and shaggy man who initially appears to be something of a physically-developed nerd, deeply obsessed with his unusual hobby. His primary interest outside of teaching is building human-powered planes, a passion that defines much of his role. This hobby reaches a successful culmination in the final episode when one of his creations flies, earning him a trophy.

Yamada is often seen socializing with the group of friends that revolves around the protagonist, Kei Kusanagi, acting as a somewhat older figure who blends into their circle. Despite his disheveled and withdrawn appearance, he possesses a notable capacity for personal change. When he decides to trim his hair and dress properly, he becomes almost unrecognizable, demonstrating a hidden potential for refinement. His personality is that of a quiet observer, but he also shows himself to be a trustworthy and honorable individual. After Koishi Herikawa experiences heartbreak following her romantic pursuit of Kei, Yamada steps in as a sympathetic confidant. He provides her with a listening ear and emotional support during her depression, and crucially, he does not take advantage of her vulnerable state. This restraint highlights his integrity. Over time, a genuine connection forms between them, and it is revealed in the OVA that he and Koishi enter a romantic and sexual relationship. Koishi also has a practical connection to Yamada, as she regularly delivers meals to him from her parents' grocery store. Yamada does not have any superhuman abilities or a major role in the central alien romance plot, but his function in the story is to serve as a unique and compelling side character whose personal journey and developing relationship with Koishi add depth to the supporting cast.