[ROYD-030] My sister is plain and modest, but when she takes off her glasses, she is a stunning beauty, and after confessing my feelings, she allowed me to insert it raw. Kinoshita Himari

In JAV, when they say “plain” they mean that she doesn’t wear nice clothes or wear makeup, not that she’s plain looking. Kinda like how S and M actually means dominant or submissive, instead of sadistic or masochistic like how we use it.