Zaibatsu

Eo Zaibatsu is the name of a group which Gavineo is in. Many believe it is not a coincidence that "Zaibatsu" is the code for Floor 0.

The Game
Eo Zaibatsu has a game. This game is called Eo Zaibatsu's Place Number: 0 and in the description, it says F3. Upon joining, a single glowing mushroom appears. When the player touches the mushroom, a larger one appears behind, illuminating the entire map, and text above that says TIME.

Meaning
Zaibatsu (財閥, "financial clique") is a Japanese term referring to industrial and financial business conglomerates in the Empire of Japan, whose influence and size allowed control over significant parts of the Japanese economy from the Meiji period until the end of World War II. They were succeeded by the Keiretsu in the second half of the 20th century. - Wikipedia.