Onee-san's Advances

A Boku no Pico fanfic. Pico is spending summer vacation at his grandfather's beach bar until his grandfather insisted that Pico enjoy his vacation, and Pico went to the countryside, where he meets Chico and the two became fast friends. After being invited to Chico's house, Pico meets Chico's elder sister. Despite Pico's age, she started to take a liking and began seducing him.