Kazuya visited his brother's house during summer vacation. He had been looking forward to seeing his sister-in-law, Kana, whom he had always admired... but that night, he happened to see Kana indulging in lonely masturbation by herself. Seeing her lewd state revived the feelings of love he had almost given up on, thinking she must be living a happy newlywed life with his brother. The moment his brother left for work and they were left alone, the passion he had suppressed for years overflowed, and he pounced on Kana...