They've been together for 12 years, and are now a family. Their parents are away on their wedding anniversary trip... it's the first time they've been alone together. Izuna has shortened her skirt because her strict parents aren't around, and she even wears makeup, which she doesn't usually do... was she always this feminine? She doesn't change her uniform, and her legs are so messy that her underwear is completely visible... and she even talks about love. She's conscious of men and women, and when she masturbates in her room, she gets caught... "Big brother, stop treating me like a kid." Her sister's seduction makes her mind go blank and she crosses the line...