Origins of Raiguko's powers

Idk if I've discussed anything about this character before, but this guy is a male. His name is Raiguko, and belonged to a clan of swordsmen (I guess samurai, since they use a traditional sized katana and wakizashi), and his ancestor wanted to become a demon in order to kill the monsters that were roaming around the world the time he was alive. To do this, he did Baki/DBZ levels of physical training and martial arts training, becoming the 2nd strongest man in the world, the first being a bakuto based on Zatoichi (the primary inspiration for this guy was Fujitora), but becoming strong didn't satisfy him. He wanted to manipulate fire and have the transformation of a goat-horned exposed fang flaming eyed demon, and also be able to produce armor made of a substance that looks like bone but it's not, kinda like the Hollow armor from Bleach. He also wanted to blow steam out of his nose, primarily for intimidation, propel himself either forwards or upwards using the fiery energy, kinda like a rocket in a way, and manipulate his body temperature by making his own body hot enough to burn someone when they touch him.

This guy was once a regular person, but then he did something to achieve these powers. How can he possibly achieve them?

There's another thing this swordsman wants. He wants to be able to pass his power to later generations through a ceremony.

The ceremony goes like this: There's a crystal ball on a altar, and the goal of the ceremony is to hold on to the crystal ball, and not let go. Sounds easier said than done, because as the chanting of the one who is doing the ceremony, who is a student of Raiguko's ancestor, goes on, the crystal ball glows orange and starts to get hot. Later on, it bursts into flames. Once the final word of the chant is said, the fire turns into a long spiraling pillar. If the attendant of the ceremony lets go, they'll have burns. Their hands will even be on fire when the orb bursts into flames. But once they succeed, all injuries will be healed.

Honestly, I could also go with having him make a pact with some sort of fire demon for those powers. Raiguko wants to rid the world of monsters and the demon wants to eventually rule the world by getting rid of the competition. He could either trick Raiguko into accepting his deal or plainly spell it out to him, leading to a final battle where Raiguko is stripped of his fancy fire powers and now has to fight the one that has been helping him throughout the story. I think that would be a pretty sweet climax!

Honestly, I could also go with having him make a pact with some sort of fire demon for those powers. Raiguko wants to rid the world of monsters and the demon wants to eventually rule the world by getting rid of the competition. He could either trick Raiguko into accepting his deal or spell it out to him, leading to a final battle where Raiguko is stripped of his fancy fire powers and now has to fight the one that has been helping him throughout the story. I think that would be a pretty sweet climax!

Adding onto that, once the demon is defeated, he reverts into a crystal sphere and then can be used in the ceremony you described!

I should correct that, it's not Raiguko himself, it's his ancestor. And that could make this guy more legendary. Plus, his statue is going to be based on the Nio Agyo statue once it's drawn. I'll consider that.

Anyone else?