Anyone who has done a "certain act" in school will become unable to take off their underwear. The only one who can undo that curse is Kamite.

A story about a noble female knight and her attempts to lose her virginity to her husband.

From ShedgeScans:

The daughter of a game shop owner finds a pocket game on the street. However, it was actually an invitation to a game of horror and slaughter!? The Game of Hell where humans are invited by the Shinigami as characters begins!