Aneki... My Sweet Elder Sister The Animation
English title: Aneki... My Sweet Elder Sister: The Animation
Japanese title: あねき… MY SWEET ELDER SISTER THE ANIMATION
Type: OVA
Episodes: 4
Source: Manga
Genres: Hentai
Studios: T-Rex, Office TakeOut
Producers: Pink Pineapple
Duration: 30 min per ep
Rating: Rx - Hentai

Takumi just cannot stop fantasizing about Saki-senpai, her voluptuous body just stands out anywhere. One day she talks to him on the train and they become friends. Whenever he can, Takumi stares at her form, always getting a hard-on. The next day he finds out they have the same fetish... and so the story begins.

(Source: AniDB)