The clumsy love story of his brother-in-law and his sister-in-law Saeko Matsushita was lewd, when his wife was busy with work and had to be away for 4 days, so she took her sister home to cook rice and water for her husband (very thoughtful). But unexpectedly, outsiders were worried about eating and drinking, and they were also worried about sex for their young and healthy brother, the two had sex with each other continuously for 4 days until their sister came home without knowing that she had been cuckolded by her own sister.