まあじゃん黙視録

Shinichi Sakurai is the protector of justice of mahjong world. One day the general of mahjong world is overthrown by a group of assassins, and the Mahjong Federation announces the world mahjong martial arts festival as a retaliatory measure in order to eliminate the soldiers of the back mahjong world. Of course hero gets an invitation letter as well.

[From vndbreview]