Gosetsu, known as Master, runs the Shin-Yokohama Vampire Hunters' Guild as its bartender and guild master. This friendly and calm former vampire hunter now manages guild operations, receiving and assigning hunting jobs, making him a central figure. He commands significant respect from younger hunters, his professional combat background contrasting with his approachable leadership. His black hair is combed back, he sports an English-style mustache, and his eyes are typically depicted as closed. His bartender attire includes a white dress shirt, black vest, black bowtie, black waist apron, black pants, and brown shoes.

He exhibits a deep affection for his daughter Koyuki, the guild barmaid, reacting aggressively to any perceived threats toward her. His fondness for dad jokes aligns with middle-aged father stereotypes. He maintains a longtime friendship with the duck-themed hunter Vamone, the only individual noted as capable of provoking him. Gosetsu is married; references exist to sexually intimate interactions with his wife during activities like hopscotch, and his specific kink is censored when exposed by Ydan Ojisan. Within the guild, he interacts with hunters like Satetsu, a reformed delinquent whose path to redemption involved guidance from both Gosetsu and Ronaldo.