My best friend's younger sister, who's younger than me but has huge breasts, looks down on me and deliberately shows off her panties! Seeing things like that... I can't stop masturbating! Shirakami Sakika SNOS-200

Saki is my best friend's younger sister; we've known each other since childhood. But the Saki I saw today, after so long, wasn't the Saki I knew. She seemed to have grown a lot in the time we hadn't seen each other. She was taller than me, and she started wearing skirts above the knee. With the slightest movement, her panties would peek out… Wow, they just peeked out a little… It was striped light blue panties. They peeked out again! With little ribbons, so cute… Her vulva had become soft and yielding, it was irresistible… Wait, had Saki deliberately been showing her panties from the beginning!? I was secretly peeking, my breath catching in my throat with excitement, had she caught me!? "Excitedly looking at a young girl's panties~" she mocked, feeling pathetic… but I couldn't stop masturbating! I want to do more panty erotica with Saki-chan!