AFRO SAMURAI

During the Chapter titled "okiku's story" at the end you will be told you must hold out until the boat comes.

here you will fight a large amount of Robot Assassins, after the first wave of them a second group of four assassins will come out on the right side of the house(from the entrance)

If you run up to them quickly and enter Focus mode(LT)and use a perfect Horizontal Slice(where the blade shines at the tip) you should cut all 4 assassins at once, nabbing you this achievement

If you screw up you can reset the checkpoint, kill the first wave and try again

(note that you cannot preform this without unlocking the ability to slice 4 at once)

At the begining of the "EMPTY SEVEN'S STORY" you'll fight androids ... kill these and an elevator cutscene should appear, when you get on the elevator (the one with the face on) you should head deeper into the ground. Now when it stops there should be shadowed staris on each side of the elevator .. if you get on these stairs and go to the furthest stair down the anroids below should gather up into a large enough group (i sliced 6 of them using the perfect horizontal slice). When you have enough ammassed then jump into them and go into focus mode (LT) and hold 'X' until the light reaches the tip of your sword ... let go and bang achievement unlocked!

One fairly easy place to do this is on the prologue chapter.

When you are fighting an entire army of Ronin, you can see a teddy bear on a porch. To the right of it, there is a small space where you can retreat, go there, back to the wall.

Wait a bit while parrying and charge a full horizontal slice.
If done correctly, you'll will slice the bellies of 4 ronins and unlock this achievement.

Note : Can not be done unless you unlocked the ability : DA FOUR GOOBERS (Wich should happen toward the middle of the game).

Towards the end of the game, when you fight the endless supply of Ninja Ninja clones on a clifftop you should have ample enemies and ample attempts to do this. Just surround yourself with Ninja Ninja clones and use horizonal focus slash charged to its fullest. You may want to work a whole group of the clones down until they are bloody, but I got it to work on a fresh supply of clones. The span of the horizontal slash hits enemies to afro's back left and back right sides. To clarify: the enemies have to die to get this achievement.

This achievement requires you to slice and kill 4 enemies at once. As there seem to be many places you can get this I have found another that proved to be rather simple and I received two 4+ kills twice in the same spot.
When you reach the Doppelganger Part 2 where you fight "The Wild Five", these are those samurais that block ridiculously, but anyway, after you fight the 5 samurais after defeating the last one run to the far side of the bridge where Ninja Ninja would have been sitting for Body Part Poker. Once you arrive here immediately turn around and fight the ninjas that attack rather quickly begin fighting them killing them is fine.

At this point you should have your back on the wall(barrier) that you cannot pass because it is the next part of the level.

***THEN, there will be like 8-10 normal guys that spawn, dudes with the straw hats or masks, let them come in behind you. WAIT for them to encircle you move out a bit so they can all get past the barrier then turn around and use the horizontal slice and there you go! ***

It may take a few tries but I had to repeat this level quite a bit trying to get the Body Part Poker achievement for the samurais and attempting this part on the hardest difficulty can be a bit of a pain. I have consecutively gotten 4 or 5 guys with the horizontal slash here. Hope this has helped you get the achievement!! =)