ZUKO-096 An extremely serious family is too earnest about sex to have a kid

You came to Tokyo to take an entrance exam. You're staying at the house of a relative you're not very fond of. Why? Because this family's four sisters are ridiculously 'serious.' Knowing about your exam, of course they start their all-out 'wrong' support for you. If it's cold, they'll warm you up naked, and they'll come to wash their bodies in the bath, collecting all your sperm for concentration... This excessive full-power support will guarantee your passing.