Same deal as Baghdad Mayhem as far as unlocking it, except you need to finish the Tokyo portion of the game.
Tokyo Raid consists of 18 islands, or "waves", that you need to pass through while accomplishing various tasks on each island. The enemy types scale faster than either Baghdad raid, but the enemies are generally more spread out .
When it comes to strategy, doing what I recommended for Baghdad Mayhem rearmed works fine. All that really matters is that you pay attention to what the objective of the wave is and what your time limit is (if you have one), other than that it is all pretty simple.