Black Cat is an anime about assassins and sweepers; the plot involves stopping twoevil organizations and preventing a young girl from becoming a weapon of mass destruction for crazy religious magicians using for their own purposes; and that is without the rare tear jerker. Its first ending song features the characters as cats. Yes, cats! See here. And if just the basis of that ending theme song isn't insane enough, it also features the Big Bad and the main character as cats... kissing.
And one of the organizations is actually not evil, and controls 1/3 of world economy, and is being antagonistic because the main character got out of the organization. Another organization's leader is a former assassin of the former organization and is creepishly sexually attracted to the main character...and both of them are male.