"A synthetic experimental weapon created secretly by Anti-Entropy to obliterate massive Houkai beasts. Kaguya operates on a tragic 15-day life cycle: every 15 days, her body undergoes self-apoptosis and regenerates from her internal core as a new incarnation. Melancholic, poetic, and deeply sentimental, she wields swarms of glowing energy fireflies and a long naginata. She intensely cherishes every passing moment, seeking to experience true warmth, friendship, and beauty before her time resets."