The 81-Square Universe is an English Shogi website founded by 1059860 and hirohiigo. Its main feature is its forum, where people from all over the world come to discuss Shogi. Registration is free. Its members range from complete novices to high-ranked amateur players.

The site began as a result of the founders, 1059860 and hirohiigo, trying to find a good shogi discussion forum, but came up empty handed. The two best choices were Shogi-L and Shogi Prospect, neither of which seemed to fit what they had in mind for a shogi forum. As a result, they created The 81-Square Universe, originally as a forum on HeavenForum.

The 81-Square Universe started out as a success, attracting many new members from around the world, with notable members such as Hidetchi, Takodori, and BCM. As the board grew in popularity, it became apparent that there was a high demand for an English shogi forum, so hirohiigo bought the domain 81squareuniverse.com and transferred the forum to there.