Fuyuno Yoshikawa is the youngest sister in the Yoshikawa family, a central household in this narrative. Her name follows a seasonal naming theme, as Fuyuno contains the word for winter, mirroring the seasonal motif present throughout her family's names. She has short blue hair, blue eyes, and is frequently depicted with a ribbon in her hair, appearing as a young girl.

As the youngest sibling, Fuyuno shares with her older sisters the inherent ability to use magic, though her primary defining characteristic is an overwhelming obsession with money and profit. When the topic of finances arises, her demeanor transforms entirely, adopting the shrewd and avaricious persona of a miser far beyond her apparent years. This fixation is a consistent driving force behind many of her actions; for example, she once expressed reproach towards her brother for failing to capture a ghost, as the captured spirit could have been a source of income. She is frequently depicted as thinking of schemes to earn cash or even swimming in it, illustrating the depth of her money fetish.

Despite her youth and pecuniary obsessions, Fuyuno is portrayed as sharp and resourceful. She is notably skilled at problem-solving and is often the one who concocts plausible excuses for the strange, magical events that occur around her family in order to keep the existence of magic hidden from non-magical people. In this sense, she plays a practical role in maintaining the household's secret, working in conjunction with her sisters to protect their brother, Haruo, from the truth about the magical world.

Fuyuno's key relationships are primarily defined by her family. She lives with her brother Haruo and her two older sisters, Maika and Chiaki. While she cooperates with them to uphold the family's magical secret and deal with the disruptions caused by the witch Ayumi, her distinct personality and specific drive for profit set her apart from her siblings. Her brother is often the unwitting straight man to her schemes, while her sisters are her partners in the larger endeavor of maintaining their magical household.

In terms of abilities, aside from general magical proficiency common to her family, Fuyuno is shown to transform into a magical girl battle outfit, a standard transformation for the witch characters in the story. However, her most notable and frequently demonstrated capabilities are her quick thinking and her talent for creating spontaneous cover stories. Her development throughout the story remains largely static, as her core personality and motivations are established early on and drive her consistent role as the cunning, money-focused youngest sister.