Hentai Series: Youkou no Ken
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?
Note: It is strongly believed that the title was originally supposed to be Nyo In (女淫道中), there was a release date with that title in 2003, but it got pushed back and eventually never came to be until it was released as Youkou no Ken in 2004. The main proof for Nyo In being Youkou no Ken is the pre-release art for Nyo In.