Fūka Mizuki is a character from the anime Trillion Game, recognized for her role as a capable and direct assistant. She is introduced as a young woman who wears glasses and works as a secretary to Gaku, one of the central protagonists, during the Great Millionaire story arc. However, her connection to the main characters predates this position. A flashback within the narrative reveals that while she was still a high school student, Mizuki worked a part-time job as a secretary for Kededoin, a significant investor figure in the series. This early experience places her at the periphery of major financial dealings from a young age.

In terms of personality, Mizuki is defined by her sharp tongue and a notable lack of hesitation when speaking her mind. She does not shy away from offering direct, unfiltered opinions to both Kededoin and Gaku, demonstrating a level of confidence that sets her apart from more passive supporting characters. Her directness is complemented by a high degree of competence. Despite still being a high school student during her first appearance in the timeline, she possesses and demonstrates advanced knowledge of corporate law, specifically concerning mechanisms like third-party allotments. This expertise allows her to explain complex financial strategies to the main characters, Haru and Gaku, during the process of Kededoin’s investment, establishing her as more than just an administrative aide.

Her role in the story is primarily that of a key supporting figure who provides both logistical support and technical expertise. She bridges the gap between the protagonists' ambitious ideas and the practical legal and corporate frameworks required to execute them. Her relationships with the main characters are built on mutual respect for her abilities, even as her bluntness creates a dynamic where she is not easily intimidated by their status or ambitions. Her development is subtly shown through her progression from a high school part-timer with sharp insights to a trusted professional secretary for Gaku, indicating a growing career trajectory within the business world the series depicts. Her notable abilities include her legal and corporate finance acumen, her unflinching honesty, and her efficiency as a secretary.