A large bonus will be awarded if the father doesn't find out about the sex three times. RCTD-442

Wearing long pants and exposing their buttocks, in three hidden locations—the kotatsu (heated floor) and the bathroom—they embark on an incestuous mission of penetration! A hefty bonus awaits those who succeed three times within two hours! Even if they've been discovered, it doesn't matter! The erect penis thrusts into the vagina with unparalleled pleasure!