This time's theme for sexual behavior monitoring is siblings. A sister at the peak of her desire engages in unexpected unprotected sex with her gross brother! Moreover! It's the sister's first experience!! The envious virgin brothers desperately try to maintain their reason...! Despite having a sense of shame, the sister, who has no concept of chastity, goes into a lustful rampage, making the brother tremble! The strangely erotic struggle between the virgin brother and the lustful sister is incredibly exciting!
