Aneki... My Sweet Elder Sister 4

Based on the manga series by Yoshu Ohepe, Takumi can't seem to get enough of Saki's beautiful senpai's form, which makes her stand out in any crowd. She meets him on the train one day, and the two become friends. Takumi glances at her body whenever he has the opportunity, constantly getting a hard-on. The next day, he discovers that they both share the same fetish... and thus the narrative starts.