Hisao Nakai is a fictional character from the visual novel game Katawa Shoujo. He is a high school student who suffers from a serious heart condition, which leads him to transfer to Yamaku High School, a school for students with disabilities. Hisao's journey explores themes of acceptance, friendship, and personal growth as he navigates life with his condition. Throughout the game, players can develop relationships with various characters, including Emi Ibarazaki, Rin Tezuka, and Shizune Hakamichi. Hisao's experiences highlight the challenges and triumphs faced by individuals with disabilities, making the story both relatable and impactful.