My girlfriend and I were not married, but we decided to live together for a while. She works in the office and I am an engineer so both have quite a stable income. One day her best friend Rin Natsuki came to my house and wanted to stay for a few days because her house was just sold so she had not found a new place. My wife also asked my opinion in advance, so Rin stayed here was quite normal for me. But her beauty made me pay attention, that night I went to the bathroom to see Rin bathing, I peeked and smelled Rin's underwear. The next day my girlfriend was on a business trip, Rin now had something to say, she saw it yesterday and then I was afraid and shame. It was surprising that Rin turned to solicit my love, how could I refuse.