Mirror Lake (カガミ湖, "Kagamiko") is a lake north-east of Ransen. It gets it's name from it's unique trait of perfectly reflecting it's surroundings, while holding a solid surface. Walking on it produces ripples and hands pressed to the surface will become wet, though it is impenetrable and therefor safe to venture onto without fear of falling through. There is a cave on Mirror Lake, though it cannot be entered through normal means.
While the lake itself is quite beautiful and mysterious, the cave is by no means attractive. It's not deep, and it only goes back so far, though it is very dark, damp and musty. It holds a foul wind to it, and gives off the vibe of something awful.
Up until the recent past, a demon had resided within the cave on Mirror Lake. A small village neighboring the lake would bring sacrifices to said demon to appease it. A bounty hunter caught wind of the demon and sought to slay it, in the process gravely wounding the beast and, in turn, being severely injured himself. The bounty hunter continues to search for the beast, for it fled before it could truly die, and it has become an obsession to this day.