Her younger sister Ria-chan is a long-limbed beautiful girl with a bit of innocence about her. One day while she was taking a nap, I caught her flashing her panties and couldn't help but stare despite knowing it wasn't appropriate. When she woke up and realized what was happening, she smiled coyly and whispered, "Do you like looking at my underwear?" From then on, every time her sister was away, she teased me relentlessly for three days straight. *Note that the contents may vary depending on the recording method.