Kōsuke Fujiwara is the younger brother of Naeka Fujiwara in the series Kamen no Maid Guy. He is a high school student, notably overweight, and an enthusiastic otaku with a particular obsession for maid-themed eroge and figurines. Despite his indulgent hobbies, he is good-natured and maintains a typical sibling rivalry with his sister. He shares a close bond with his wealthy grandfather, Ōfujiwara Zenjūrō, and is genuinely grateful for the arrival of the maid Fubuki, whom he regards as a prized asset. His otaku inclinations frequently draw him into comedic entanglements and occasionally put him at odds with the other characters. When forced to go on a diet, Kōsuke is revealed to be quite handsome, though he soon reverts to his usual habits. In the story, he serves primarily as comic relief and an occasional source of practical knowledge about maid culture, but he does not possess any notable combat abilities or undergo significant character development. His role is that of a secondary character who supports the main cast, often by providing insight into otaku culture or unwittingly participating in the chaotic schemes of the masked maid Kogarashi.