Asphyxia ~ The Mystery of the Fireball and the Perfect Closed-room Murderer

A man is found murder in a hotel room, there is no sign of force-entry, no sign of struggle, and witness claims no one has entered the room besides the victim. Another witness who works in the building across from the window claims to have seen ghost fire - a statement that interests Yukawa and prompts him into uncovering the secret behind the man's death.