The school festival is in full swing, and Yuuna is the star of the show. She may be a ghost, but that's not going to stop her from appearing in the school play as the Little Mermaid. But soon after, the residents of the Yuragi-sou inn find themselves trapped in a magical, cursed board game. To escape it in one piece, they'll have to stay on their toes: every single space on the board carries uniquely perverted consequences!