Mio Fukaya is a university student and the central female protagonist of the story. At a class reunion, she reunites with Takahide Kujō, her first love from middle school, only to discover that he has become a priest at his family's temple. Initially assuming that his religious vocation would preclude any romantic involvement, Mio is surprised when the two share a passionate night together. She is portrayed as a kind-hearted and caring individual, though she often finds herself flustered and conflicted by the secrecy and moral complexity of their relationship. Her motivations are rooted in genuine affection for Takahide and a longing to recapture the feelings she had for him during their school days. Throughout the narrative, Mio grapples with the tension between her desires and the societal and religious expectations surrounding his priesthood. She learns about the challenges of being a priest's wife through interactions with his family and the temple's community, and ultimately makes a conscious decision to commit to the relationship despite the difficulties. Her role in the story is that of the primary emotional lens through which the romance unfolds, and her personal journey involves reconciling her love with the realities of Takahide's life. She does not possess any supernatural or extraordinary abilities; her character is defined by her emotional depth, loyalty, and gradual growth in understanding both her own feelings and the responsibilities that come with loving a priest.