It is the cat-shaped fortress of Nekomata which is guarded by numerous ninja cats. The ninja cats have shown to not take kindly to humans, as Team 7, who were on a mission to retrieve Nekomata's paw print, had to "disguise" themselves as cats to infiltrate the fortress. It is shown that it isn't completely a fortress as there were restaurants and bars seen within it and that were civilian cats as well. One of the ninja cat guards that Sasuke Uchiha questioned had a headband with the kanji for truth or sincerity (誠, makoto) written across it, like all the hidden villages have.