Senran Kagura, that booby ninja game, is apparently doing pretty well in Japan. Even Sony's Shuhei Yoshida bought a copy.
Those who own the game might want to be careful of a bug that will trap them in boob hell. The bug doesn't appear to be that easy to find (it involves using the character Ikaruka in the "Inran Mode" and then unleashing a series of slash attacks on the boss character).
Some might call this a bug, others might call it a feature — an easter egg, even!