The life of the young couple Shinoda is very happy until his sister Kashii comes to the house to play on a beautiful day. It was also the first time Kashii met his wife, and when they met, the two seemed to have a pre-existing relationship, especially her sister, and until she left, perhaps in her eyes there was a very deep intention in her mind. Not unexpectedly, on the day Shinoda and her husband held a small party that invited Kashi and her husband to come, this time she prepared a very sinister plan to be able to seduce his wife. Without noticing, she secretly put sleeping pills in her sister's cup, and not long after, Kashii's husband was responsible for bringing her into the room, and it was at this time that the bastard had engaged in lewd sex and raped his sister-in-law. As for the other couple, Kashii can easily seduce his brother-in-law with just a few simple moves, and the clumsy love between them also begins to happen from here.