Runa Kagurazaka, alias Kaguya, is a 15-year-old male. His real name is Tsuki Kagurazaka. Born into a politically prominent family, his strict upbringing instilled well-mannered behavior early on, fostering a calm, diligent, and independent nature. He excels in diverse disciplines including violin, piano, horseback riding, clay pigeon shooting, and the Japanese tea ceremony. Despite his reserved personality, he acts freely, unconstrained by prejudice or societal norms.

Recruited by his childhood friend Kokoro Hanabusa, Runa secretly performs in the idol unit Pop'N Star, hiding this from his parents, especially his father. Though initially hesitant about cross-dressing for his idol persona, Kokoro's influence led him to accept the role; he gradually embraced exploring its possibilities. His striking appearance features long, semi-wavy light blue hair extending past his hips, fair skin, and pinkish-plum eyes, creating a feminine presentation. He stands 159 cm (5'2") tall and weighs 47 kg.

Beneath his feminine guise, Runa demonstrates reliability and assertiveness. He often laughs quietly and possesses an interest in the occult. Within his unit, he naturally supports fellow member Momosuke Oikawa, who faces similar challenges, due to his caring inclination. His hobbies include clay pigeon shooting, and his food preferences favor crepes while he dislikes liver. His birthday is November 11.