12 Years of Desire Explodes: 3 Days of Sibling Passion

Synopsis

Step-siblings for 12 years, now a family. Parents away on their anniversary trip—their first time alone together. Without strict parental oversight, Izuna shortens her skirt and applies makeup unusually. When did she become so feminine? She keeps her uniform on, sits carelessly in short skirts, and talks about romance. Noticing her as a woman, he masturbates in his room only to be caught. “Big brother, stop treating me like a child,” she whispers, and his mind goes blank as he crosses the line.