Following the popcorn, which unintentionally earned itself the nickname "Lightning Corn," the next products in the Yamano Territory Specialties Strategy are the board games Reversi and Shogi! In this world where entertainment is scarce, it's impossible for Earth's long-running hit games not to be knockouts. That said, the board games first need to be made popular and then the sales rights monopolized. So, Mitsuha decides to start her attack at the top of the country and asks Princess Sabine for help in getting the King and the Prime Minister to realize just how fun the games are. However, she never imagined that this would ignite a new ambition for the Little Devil Princess...!!