It sounds like you're looking for information on the tenth episode of the anime (also known as More Than a Married Couple, But Not Lovers ).
In a humorous post-credits scene, Shū leads the boys to the girls' room for a card game. When they open the door, they find the girls wearing facial masks, which terrifies the boys. Series Background [AnimesTC] Fuufu Ijou, Koibito Miman - 10.mp4
The story follows a high school "marriage training" project where students are paired up to live as couples. It sounds like you're looking for information on