Mari had always loved her brother, Tsuyoshi, who used to excel in both studies and sports. Now, however, he has suffered a setback and is a shut-in NEET. One day, Tsuyoshi, from his room, makes a proposal to Mari: "Let's play the King Game!" Because of her incredibly devoted nature, Mari agrees to play. Then, Tsuyoshi, having become the King, gives her an outrageous order... "From today, I'll be the King for two whole days, so you must obey my every command without question!!"