Will unlock on Level 22
Story related and cannot be missed.
He's the toughest of all bosses, but you are tougher!
No button sequence this time... Kuji Magic is the key!
First, you will want to equip all the 'Storm'-like spells that you can access by pressing while in combat.
Be sure to have enough Flasks of Strong Ginseng, and enough Healing Potions or anything else that can restore your health (sushi, honeycomb, ...)
This boss his health is also his defence. The balls spinning around him, are his shield. Destroying those balls, will lower his health as well!
Keep an eye on your health at all times!
Kill the minions as soon as possible, as they'll only get in your way
When you see the purple-black magic coming to you, swing your sword to send it back to him (as with the mages in the game, remember?). This will stun him for a while.
Beware when he's lifted, as he will have special attacks. His lightning attacks can hurt you badly!
When he's lifted, sprint by holding across the edges of the map to avoid being hit by his special attacks for most of the time
The way I did it: I only used Meteor Storm to attack the spinning balls. Immediately I recharged my Ki energy by selecting the Flask of Strong Ginseng from my inventory by pressing . If I had a new opportunity, I used the Meteor Storm immediately again, otherwise I was killing the minions.
Once he was lifted, I ran around the map holding (got hit a few times though, but immediately drank a healing potion). As soon as he was back on the ground in the middle, I ran up to him and used the Meteor Storm again. Keep repeating this strategy a few times, and his spinning balls should be destroyed after 3-4 Meteor Storm attacks.