A beautiful older sister who has special feelings for her younger brother requests SOD's cooperation! Three pairs of siblings are lured in under the pretense of a stay-over monitor experience, and are then left alone in a love hotel for monitoring! Under the pretext of a survey that could earn up to 100,000 yen, the perverted older sister plays naughty pranks on her virgin younger brother, trying to close the gap between them! The younger brothers accidentally get an erection when they touch their mature older sister's naked body...