Dial Q o Mawase!

From the same people that brought us Divine Sealing, Dial Q Wo Mawase! is a hentai Mahjong game. The player takes the role of a private detective hired by a woman to dig up dirt on her husband. In doing so, he goes to a secret underground mahjong club, where he must defeat young girls to extract information -- and their undergarments.

The mahjong itself is strictly a recreation of the traditional Chinese board game. However, after each round the player wins, the opponent will remove a part of their clothing, until eventually they are completely nude. After defeating an opponent, they will give you the phone number of the next target that must be interrogated, which doubles as a password. There are six different opponents to play against in total.