The boy "Nao" is small in stature, but his penis is unusually large. One day, his sister-in-law Chiaki decides to have a viewing party with her friends for her brother's complex penis. The two girls invited were Nagisa, a blonde-haired gal and Yukiko a neat, black-haired girl. While teasing each other, the two friends become more and more excited to see the oversized penis for the first time and they can't stop themselves...!