Nao is a boy small in stature, but with an unusually large penis.
One day, Nao’s sister-in-law, Chiaki, decides to show off her brother’s oversized penis. The two girls invited are Nagisa, a blonde-haired gyaru, and Yukiko, a neat, black-haired girl.
The two friends are teasing him, having never seen an oversized penis before. They get more and more excited, and they can’t stop themselves…!