Hikaru, the older sister, is quiet and withdrawn. Luna, the younger sister, is outgoing, slutty and sociable. They are twins, but their personalities are very different. Hikaru admires the popular influencer Kouki. Luna is Kouki's sex friend! "I want Kouki to hold me!"Hikaru masturbates, feeling lonely. For some reason, her older sister Hikaru ends up disguising herself as her younger sister. Kouki is confused and doesn't realize that she is being disguised, and from there a parallel (?) squishy sex session begins!