Natural 2: Duo
Japanese title: ナチュラル2 デュオ
Alternative titles: Natural Obsessions 2
Type: OVA
Source: Visual novel
Episodes: 4
Status: Finished Airing
Aired: Nov 25, 2001 to Jul 24, 2003
Duration: 28 min per ep
Rating: Rx - Hentai
Studios: Arms
Producers: Green Bunny
Licensors: Adult Source Media
Genres: Hentai

Chisato and Kuu lost their parents years ago and were taken in by an Old man and his grandson, Chisato and Kuu became good friends with his grandson however he left and never came back. Now. Years later Chisato met up with her "Onii-chan" her lost love.

(Source: ANN)