Youkou no Ken
English title: Samurai XXX
Japanese title: 妖香の剣
Type: OVA
Source: Original
Episodes: 2
Status: Finished Airing
Aired: May 28, 2004 to Jul 23, 2004
Duration: 28 min per ep
Rating: Rx - Hentai
Producers: Green Bunny
Licensors: Media Blasters, Kitty Media
Genres: Adventure, Comedy, Hentai

Feudal Japan was a land beset with warfare and strife. Families were torn asunder and siblings were divided by conflict and chaos. Matagoro Yoshimura has been hired by the feudal lords to seek out a treasure of incredible wealth —but there's a catch... the only way to find this cache is by gathering the pieces of the map that have been hidden on the backs of female ninja scattered throughout the land. The only time these hidden maps will reveal themselves is when the ninja carrying it is in the throes of passion. Is Yoshimura "up" to the task of putting together the puzzle pieces and finding the treasure? 

(Source: AniDB)