Aneki... My Sweet Elder Sister: The Animation

Using the manga by Yoshu Ohepe.

Takumi just cannot stop fantasizing about Saki-senpai, her voluptuous body just shines anywhere. One day she foretells him for the train and they also become friends. Whenever they can, Takumi stares at her form, always receiving a hard-on. The very next day he learns they have similar fetish... and the story begins.