HELI-X ~Spiral Labyrinth~ [「HELI-X 〜スパイラル・ラビリンス〜」]

The fourth play in the 'Heli-X' series. When Sadness woke up, she was alone in a dimly lit place. A small ray of light illuminated the knife in her hand. When she looked at the ground, she saw a large pool of blood and a motionless body... A corpse with a face she recognised. Was Sadness the one who killed them?