Sakura Labyrinth

The mysterious structure that appeared on the far side of the Moon.
It mimics the arena of the Holy Grail War on the surface. It is an area that continues to maintain the existence of real numbers inside the imaginary number space, where maintaining a fixed form is a difficult task.
Nestled closely around the trunk of a giant sakura tree, it wraps further and further down. This is the source of the name Sakura Labyrinth. The student council deems the Sakura Labyrinth to be getting out of hand and comes up with some alternative plans for it, but all the plans are pretty bad….
By the way, initially it was called Sakura Dungeon. But the directness of this name, which evokes the idea that you have to bust in and clear everything inside, was thought to be pretty disgusting, so when the new visuals for this area came along the name was axed and changed to Sakura Labyrinth. With this we managed to decrease the amount of linguistic obscenity in CCC.

Fate/EXTRA Material: Encyclopedia of Fate/EXTRA