Gundou Sensei, Sore Ron desu!

A VTuber named Mirei Gundo partners with Osamu Saitou, a character from a mahjong game she summoned, to operate a struggling mahjong parlor. As a beginner in mahjong, she must learn to manage her clientele and attract more visitors to keep the business afloat. If she fails, Osamu Saitou will vanish. With the parlor's future at stake, Mirei works to revive its fortunes despite her lack of experience.