The year is 2035. A series of mysterious incidents began to occur in Tokyo. Young women disappeared under strange circumstances, and returned brainwashed, commanding armies of bionic monsters and assaulting human settlements. Such women were called "Possessioners". A special all-female squad was formed to face them in combat and bring them back to humanity.

Houtei Raoyui (a Sino-Japanese term referring to winning a mahjong hand by the last player's discard) is an adult-themed mahjong game. The player assumes the role of a male student in a private high school, where he must compete against seven female opponents in the game of mahjong. The mahjong is always of the one-on-one variety. All the characters except …