Sōhei Fujii, a human classmate of Yuki, transfers to her school at age nine in fourth grade. He has black hair, brown eyes, and often wears striped shirts with shorts. Initially intrigued by Yuki's unusual behavior and scent, he persistently observes her, leading to an accidental attack where Yuki, in wolf form, injures his ear. Despite this, he protects her by claiming a wild wolf caused the injury, preventing repercussions for Yuki.

Sōhei displays a friendly, forgiving personality, frequently using humor in social interactions. He feels neglected due to his mother's remarriage and pregnancy, believing he will become unnecessary after his younger sibling's birth. This sense of abandonment fuels his expressed desire to run away and pursue a solitary life as a boxer or professional wrestler, describing himself as a "lone wolf." His keen awareness and emotional sensitivity are evident, particularly in detecting Yuki's hidden nature.

Two years after their first meeting, a severe storm strands Sōhei and Yuki at school. In this vulnerable moment, he confides his familial insecurities, prompting Yuki to reveal her wolf identity and confess her role in his injury. Sōhei admits he always knew her secret but chose to keep it concealed, reaffirming his promise never to tell anyone. This exchange deepens their trust and friendship.

Sōhei's role extends beyond companionship; his acceptance of Yuki's dual nature provides crucial emotional support as she navigates her identity. His own struggles with belonging and his nonjudgmental stance toward Yuki's secret highlight his empathy and loyalty.