SCPX-108 Close siblings challenge! Two people alone in a secret room, taking aphrodisiacs for the first time! The shy virgin brother and kind sister take on an H mission. Will they, with their crotches slick from arousal fluid, be unable to hold back and

A genuine pair of close siblings take on a monitoring experiment for the prize money! Titled 'Where is the line between siblings and opposite sexes?', they thoroughly examine just how far sibling intimacy can go (after secretly making them drink an aphrodisiac). Though embarrassed, the two complete their mission, but end up having unprotected incestuous sex as things heat up! It's so envy-inducing that the sister helps her brother lose his virginity!