Louise Frois, a Portuguese Christian missionary serving in Sakai’s church, dedicates her life to spreading faith in Japan. Her blonde hair and blue eyes contrast with the dark fabric of her traditional nun’s habit, while her initially self-perceived “sinful” physique fuels inner conflict. Calm and composed, she balances compassion with sharp intellect, extending kindness even to figures like Bontenmaru, who embraces the identity of the apocalyptic beast "666."

Her devout spirituality intertwines with pragmatic insight. After Yoshiharu Sagara, a time-traveler, shares his origins, she accepts his story without hesitation, interpreting his presence as divinely ordained. Though drawn to his unconventional perspective, she reaffirms her vows through whispered prayers during their interactions. Her strategic mind aids Yoshiharu in deciphering Nobuna Oda’s jealousy-inducing tactics, showcasing her grasp of human psychology.

Patriotism drives her resolve to inform Portugal of the link between rats, the Black Death, and feline persecution, hoping to curb the pandemic. Introduced in the Kyoto Arc mediating a clash between Yoshiharu and Bontenmaru, she later solidifies her role as both spiritual guide and confidante, bridging cultures through scripture and quiet diplomacy. Her journey weaves self-acceptance with service, harmonizing duty to God, homeland, and the community she adopts in Japan.