The Mini-Maze (FC迷宮, FC Meikyū, FC Labyrinth) is an area accessible from the Day & Night Towers.
It is a dark, first person maze that is hard to navigate through without looking at the map screen. On the map, it has red brick walls, a grey tiled floor and red staircases that either transport you to other parts of the maze or different areas. When the map is zoomed out, the paths resemble the digits of Pi.
There are also many invisible walls/openings in this area that can be determined on the map screen by their small deviations: invisible openings have a brick wall texture that's flipped upside down, and invisible walls have a path texture with it's diamond shape a bit smaller than usual. The Glasses effect will make it more obvious: the openings will be shown and the walls that were once invisible are now grey bricks.
The menu screen usually accessed by pressing X is also different in this area. It lets you choose from only four options: Menu Close, Eyeball Bomb, Awake From Dream and Manual. The Manual option gives you instructions on how to maneuver throughout the maze.
The Eyeball Bomb effect can be found in this area, but it requires a lot of effort. You must find your way to the top right of the map within a large rectangular area, and will need the Glasses effect to see the invisible walls here. Travel bearing north-east through the now visible maze and try to go through the path that passes through the red bricks. At the end of this path you will trigger a switch which makes all the grey walls disappear. Back at the entrance from Red Brick Maze, go up the staircase below you to a crossroads area. Go up the staircase on the right path. On this "floor", there should be a spinning eyeball bomb icon on the map screen. Walk to it and interact with it to get the effect.
On the same floor as the Eyeball Bomb effect is another staircase. Going up it will take you to the Day & Night Towers. Going left at the crossroads area takes you to the Bathhouse. Going right at the crossroads and taking the staircase on the right from that corridor will take you to the FC Basement.