Cassy was only wearing a short, sleeveless black nightgown made out of silk and no panties or bra under it. She liked the feeling of her nipples rubbing against the soft material. Seeing her sisters exposed breasts wasn't that rare, they saw each other naked from time to time and even used to take baths together in the past. But then something came up and they stopped washing each other for some reason. Cassandra loved Lisa, but only as a sibling and had never any stronger feelings for her. That was until their soft lips got pressed together all of a sudden. She didn't move away or protest in any way when Lisa's face came closer with each passing second. It was at this moment that her heart began to beat faster. The straps of Cassy's nightgown slipped down, followed by the black silk and exposing her breasts thanks to her movements. She followed Lisa's instructions and did her best to return the kiss before she was pushed down. Her arms wrapped around her sisters body as if she feared that their embrace could end too soon, her eyes were closed while their tongues were exploring the taste of their mouthes. Cassy didn't know what was going on, but she wanted more of this warm, tingling sensation. She didn't notice that her pussy became moist and simply enjoyed the sensation of their breasts being pressed together. If this was a dream, then she didn't want to wake up.