"Based on data gathered, I've worked out that it's an underground structure that superficially resembles the Tokyo subway system. It's populated by Shadows, which are unintelligent but hostile creatures born from humanity's subconscious beliefs. The deeper you go, the stronger they get and the more inhospitable the atmosphere becomes. Trying to map the tunnels is unfortunately pointless, since every time you enter they have a different configuration."

He cracked his neck. "Apart from that, I haven't been in here yet, so I'm not certain what to expect."