Unbalance
English name: Sibling Secret: She's the Twisted Sister
Genres: Hentai
Type: OVA, Episodes: 3
Aired: Jun 28, 2002 to Dec 27, 2002
Studio: AT-2
Source: Visual novel
Rating: Rx - Hentai
Synopsis:
The Hungry Bear is a restaurant where carnal appetites are satisfied to order. The waitress, Mika, has just uncovered the secret life of her late sister, a woman who would perform any sexual act, no matter how bizarre! But the secret's all in the sauce, and Mika vows to service her clientele's insatiable appetite for the exotic!

(Source: AniDB)