My girlfriend's younger sister (Kanon), who I'm tutoring, is really into sex! I promised her that I wouldn't have sex until we got married, and I'm getting anxious because we only kiss...Kanon, who was eavesdropping on their conversation, says, "Shall I be your sex practice partner? I can do it, Kanon?" She flashes her panties, gets close to me, whispers...I try to refuse her devilish provocations, but my pussy is rock hard! Once I let loose, I can't stop myself and we have sex behind my girlfriend's back! I'm totally smitten with the cute Kanon...