From website:

Fursona and Black Tokyo meet in the Tatakama.

Japan has a long history of strange hybrid monsters, of ghosts and spirits that are half animal and yet, somehow, half human. Some of these creatures are famous, and appear in popular culture outside of Japan- sexy Kitsune, cunning Tengu and other hybrid folk. Others are obscure but no less impressive for that- the great, earthquake causing namazu, the Tanuki and their endlessly mutable testicles, and other strange creatures.

This sourcebook describes how to integrate the freeform ‘furry’ character creation system described in Fursona: The Definitive Guide to Creating Anthropomorphic Characters (Otherverse Games, 2011), into a hentai-inspired campaign set in the Tatakama. It is a companion to the upcoming Black Tokyo Legends: Races of the Tatakama, and some concepts only hinted at here will be fully explored in that release.

Black Tokyo and the Tatakama
The concepts presented here had their origins in Black Tokyo, a guide to playing hentai inspired horror/adventure using the D20 Modern ruleset. This sourcebook deals with monsters and demons in their natural habitat, on the far side of the dimensional barrier that separates the endless
twilight of the Tatakama from the skyscrapers and bullet trains of Black Tokyo in modern Japan.

This sourcebook provides new ways to use the character creation system found in Fursona: The Definitive Guide to Creating Anthropomorphic Characters released by Otherverse Games in 2011.

It is not a standalone sourcebook and it also heavily references the upcoming Races of the Tatakama sourcebook.