It was agreed that penetration would only last 10 seconds! However, she ended up having multiple orgasms because her father-in-law's penis was so perfectly in sync. (Ebi Saki ADN-755)

After my wife left, my father-in-law couldn't even eat. I told him to just ask for anything I could do. But I never expected things to turn out like this... He said he wanted to penetrate Riko, just for 10 seconds! Didn't you say you'd do anything? I thought it was just a 10-second agreement, but our bodies were so perfectly in sync that I couldn't stop myself from orgasming...