Yoshinaga Reiko (32) has been married for two years and has no complaints about her husband. However, she is cheating on him. The other woman is Koyama Emi (26), a woman who recently moved into the apartment building. Today, Reiko plans to invite Emi over while her husband is out, and for them to indulge in mutual pleasure. As the anticipation grows, her eyes get watery and her crotch gets wet. Then, when the doorbell rings and the door opens, the two fly together like sparks have exploded, running their tongues over each other's lips.