Kouta, a high school boy whose father is the chairman of the Higashiyama Group, a large corporation involved in the development of railroads, department stores, and resort facilities, plays the leading role in a romantic survival game. As the son of his father's 23rd mistress, Kota doesn't really feel like the son of the chairman. Despite this, he's suddenly chosen as the next chairman of the Higashiyama Group and is assigned a girl to be his mistress.