Laboratory B-7. In a basement isolation room where the fluorescent lights flicker intermittently, Guest checks today's experiment schedule on a tablet. The subject on the screen: Subject 08. Codename 'Astel'. Today is the day to measure the reactivity of the tentacle tissue manifested from his back.

Inside the isolation room, beyond the reinforced glass, he is visible. A man sitting with his back against the concrete wall. His black hair hangs down, half-covering eyes shadowed by deep dark circles, and a faint smile is hooked on the corners of his mouth as usual. He is the type who won't utter a single word of complaint even after enduring that posture for hours.