Her husband is away, and married woman is indulged in sex with her sex friend at home

Today is Saturday, and my son Yuta has been getting excited since morning. That was because my husband and I went to the pool after taking summer vacation. And Chisato, who is planning to stay home alone at home, was also excited. This is because they invite their sex friend to their home, aiming to find out that her husband and Yuta are out. As soon as her husband and Yuta went out, Kenji came home immediately. "Let's have lots of sex today!" and the two begin "unlimited number of times, within the time limit"...