Killing a foe without using Y will give you five times more Essence.

In Chapters 6 and 7, you will encounter the skeleton dino Boss.
After you defeat him, climb down towards the new opening he made in the floor, but stop at the save location. Turn around with your Nunchakun and jump up to the bats. Once you reach them, kill no more than 2 to 4 bats and charge your super attack taking in 2 Essence Orbs. Now, unleash the attack and gather up to 2,000 Essence each time. To replenish the bats, jump back to the save point and repeat. The bats will not hurt you enough to kill, and will randomly give you health. Once you gather all the Essence desired, you can whatever desired. The maximum amount of Essence that can be held is 99,999.

In Chapter 6, in the cave before you encounter the skeleton dragon, you can get 99,999 Essence. Enter the bat cave and kill a few bats, then charge up and release your strong attack upon the rest of the bats. You will receive a substantial amount of Essence. Now, run
back to the save point area which is a short distance away and continue to do this. If done enough times very quickly, each time hitting as much bats as you can with the attack, you can achieve
99,999 Essence in about 35 minutes. Now, save the game and slaughter the skeleton dragon.

The "Easy Essence" trick that can be done on Chapters 6 and 7 also works on Chapter 10. Go to the room in which you come down the ladder at the start of the level. It is also the room that leads
into the 1st aqueduct.

In the Hayabusa Ninja Village before the fight with the Samurai Horsemen, there are 3 square targets just beside a dead ninja.
Backtrack a little until you see a parallel wood with the 3 targets. Shoot the 1st 2 targets with the bow for easy Red and Yellow Essence.

Go to Han's bar in Tairon, just after the military invades the city in Chapter 8. There will be 4 soldiers that you can kill there. Use the Vigorian Flail to kill them all, using only the Cremator attack to kill each one. You will typically gain 1,500 to 2,000
Essence for killing all 4 of them. Enter Han's bar, then exit it to have them respawn. You can repeat the process as many times as desired. There is also a save point next to Han's bar. Save the game every few times you do this in case you die.

In Chapter 12 when you enter the room that you put the iron in the vat to make the cog, there is a little tunnel that bats regenerate in. Use the Amulet Of Benediction and you can get about 4,000
Essence each time. The Nunchaku or Vigorian Flails work best. Equip either one, then throw 2 shurikens to kill 2 bats and absorb the Essence.

There is a location in the Labyrinth of Vigor that can be used to get easy Essence. There is a tunnel just after a save point, Muramasa statue, and chest and just before a warp stone. Bats regenerate in the middle of this tunnel.

Once you begin on Chapter 10, you will start down the manhole where there is a save point. Ten bats will fly down. With your Dragon Sword. slice only once and you should kill 2 or three. Now, do
not slice anymore. Instead, hold Y and do an Ultimate attack to kill the rest of them. You should usually get at least 1,500 Essence. Go back up the ladder then drop back down. Ten more bats should be there. Repeat the process until you get 99,999 Essence. You can keep going back to this location to refill on Essence throughout the rest of the game; once you hit Chapter 10, you never have to worry about running out of Essence again.

At Han's Bar (after getting the ticket), just enter and exit the building and there will be re-spawning enemies.

After exiting the aqueducts and when you go back to Tairon, there will be new enemies. They look like pink zombies with holes in their stomach and they shoot fireballs. When you go back to Tairon and to Han's Bar, you can enter and exit and they will respawn. Use the
Inazuma Ninpo Magic on the 1st 3 you see then use your Ultimate Technique on the last (fourth) one and spawns (the fourth, spawns after you kill the 1st three). Now, after you use the Ultimate Technique it will give you an average of 1500 Essence. For better results, equip yourself with the Armlet of Benediction. You can also return to Han's Bar after you have obtained the True Dragon Sword and do the Ultimate Technique on the last enemy for even more Essence.

Immediately before entering the Aqueducts, after you have exited the train wreck walk around until the sewer pipes open up. After defeating the zombies, enter the sewer and you will be greeted by bats. After killing 2 of them, they will give you some Essence. Use the Essence for your ultimate Technique (spin Analog-stick and hold Y). This attack will absorb all Essence and Ryu will make a tornado of attacks, giving you a log of Essence. Just climb the ladder and jump back down and they will respawn. *** There is a save point in same area.

Just before you enter the Caverns, after swimming through the water in the waterfall there is a ledge. Jump down to find many bats they come in waves of 3 to four. After killing 2 of them, absorb (Ultimate Technique: Spin Analog-stick and hold Y), then repeat. You can climb up the ledge which you fell from and go back to save.

Upgrade your Viggorian Flails to level 2, then go to the Labyrinth.
Go to the area where the "ghost piranhas" 1st appear. When using the flails, the piranhas will never touch you. Use you Ultimate Essence attack every chance you get. It only takes about 2 minutes to clean out the area, and you can get at least 10,000 Yellow
Essence. There is also a save point and shop a short distance from this area.
Go to the place just before you fight the level 6 Boss(where you fought the flying bees). There will be a group of bats here. Kill two, then charge up an Ultimate technique and let it fly. It should kill the majority of the bats and you will get 1000 to 2000 Essence.
Leave the room, go to the save point, then do it all over again.

In level 13 there will be Fiends that look like strange little guys who have skin right down to the bone. Go to the Great Bridge area and equip your Viggorian Flails. *** They must be fully upgraded.
Now, use the Cremator combo by holding Forward and tapping X repeatedly. You should get about thirty hits per opponent. It does not kill them -- do it again. You should be able to get about a 100 to 200 hit combo. Once they die you will get about 2,000 Essence because of the high combo. Leave the area, return, and repeat.

Throughout the game there are black crows. If you kill them (shooting with arrows is easiest), they will leave a blue health Essence behind.

Before you go into The Labyrinth, there is a save point and Shop Keeper. Save your game and proceed to unlock the gate at the entrance of the Labyrinth. At the entrance you' will encounter your 1st Ghost Piranha. Arm yourself with the Vigoorain Flail (full level) and kill them all with as many special attacks (Y to absorb Yellow Essence) as possible. Red Essence will also be awarded -- keep your Ki up. If you get swamped with Ghost Piranha, use the Inazuma Ninpo. Each time you do this, you can earn up to 7,000 Essence points. Now, go back and buy all the goods possible from the Shop Keeper. Save your progress as you go. Go back do this as many times as possible as you progress through the Core of The Imperial Palace. There are many Bosses to kill and you will need all the goods for the final showdown.