Speaking of summer, the sea! Speaking of summer, it is a mountain! And speaking of summer...... She's a naughty older sister! ! During the summer vacation, Yuki was left in the countryside where his grandfather's house was located. When I was completely bored with the lack of stimulation every day, a big-breasted older sister who had too much free time appeared. "My sister will be my playmate," she said, so she brought Yuki-kun home and took the naughty virgin boy ...... cue ball! The ultimate virginity graduation from the colossal breasts writer and the reverse mata. Expectations rise with obscene words whispered in my ear. The only entertainment in the countryside is sex - city boys are helpless to the older sisters who have acquired skilled techniques! "I wanted to meet such an older sister~!"