The protagonist, Kogawa Daisuke, gets invited by his brother to freeload at the place where his distant relatives, the Takamine Family, live. It's a residence resembling a millionaire's mansion where maids take care of the household chores and the food is nothing but magnificent.

He was suspicious of the ordeal, but still went with the request.

However, as he arrived, three sisters with equally huge breasts, asses and backs were awaiting him: