Yuna and Yui are close step-sisters. Although they both started families and left home, they were dissatisfied with their lives and returned to their parents' homes. As they drink and reminisce about old times, the topic of conversation turns to the baths they used to take together as children. In their drunken state, the beautiful sisters end up taking a bath together. When the sisters see each other's naked bodies as adults, they get in the mood...