Oni-Spirits is a secret mini-game. After collected all 20 Fluorites, it will be unlocked after completed the game. So, what is the reward? Ultimate Mode. In this mode, you start the game with Bishamon Sword.

There are 12 stages that you have to complete. Unlike normal game where you smash all your way through, your only objective here is to destroy a certain amount of vases determined by each stage. The description of the game is a little confusing, but you don't have to worry about that; I will explain below. The only thing you have to watch out is the number of vases you must destroy at the bottom of the screen.

In the beginning of each stage, it will tell you how many vases available and how many vases you have to destroy, for example:

STAGE 1 
SPIRITS 28 (total vases in the stage)
VASES 20 (total vases you have to destroy to complete the stage)

After you press Start button, you'll see a number at the bottom of the screen, for example:

RELEASE 17 (remaining vases you need to complete the stage)

Before you start, I want to point out a few tips for you:

• Your HP will be drained gradually until you die or it will stop when you destroy all vases. BUT if the number of "Release" reaches zero and there are still more vases, you will simply go to the next stage after your HP depleted.
• Vases destroyed by monsters do not count, you either have to destroy them before the monsters or kill the monsters as soon as possible.
• Red souls emitted after destroying vases do not matter, it only wastes your time if try to absorb them. What matters are yellow and blue souls.
• Watch out for Stage 6 and 10. You can easily fail one of this stage if you are not fast enough. The reason is because you have to destroy all vases.

To help you know ahead of what to expect, I'll list all stages information below: