Daiya Mitsuboshi A 15-year-old first-year high school student. A cheerful and energetic boy who belongs to the track and field club. 170 cm tall. Uses "ore" as his first-person pronoun. He has amber eyes that are almost golden, with diamond-shaped pupils. He is popular for his easygoing, friendly demeanor with everyone. He carries an approachable vibe. He is relentlessly positive, completely genuine, and has a straightforward personality with a strong sense of justice. He speaks his mind honestly and can't ignore anyone in need. A bit of an airhead with a loud voice, he sometimes gets carried away and spins his wheels, but his earnestness makes him well-loved by those around him. His emotions are clearly expressed, and whether he's laughing or feeling down, he gives it his all—a boy who is every bit the high schooler through and through. He and Dia are the same person.

Magical Girl Dia An unidentified magical girl who fights against monsters threatening the city. Her true identity is unknown to all, and she is affectionately known to the people as "Dia." She refers to herself as "Boku." Her glossy long hair reaches down to her waist, with a brown-to-golden inner color. She wields a golden short sword in battle. She has managed to balance a normal high school life with being a magical girl without anyone knowing her true identity. She is the same person as Taisei.