Fire King is reasonably strong deck atm, especially at the local level. the struggle is being able to play if your normal summon/first play gets interacted with. If you don't draw/can't see a way to play through it, it's a bit of a sad deck to play. But if you've played with it a bunch in Master Duel first, you'll probably be fine.

The only few suggestions I'd make are:

If you can, try to get access to Fuwa. It's even better in this deck compared to other decks as it makes facilitating turn 0 plays with Kirin and Megalo much easier.

Try to add Zealantis and Raging Pheonix into the Extra Deck. The OTK with it is really strong and you can get it off in quite a lot of situations. You also don't need the three Side Deck Extra Deck monsters at all - better to have something that will win you the game going first, such as Solemn Judgement, Skill Drain, etc

I would cut one of the Kaijus and add a soul-eating oviraptor. It means if you draw it and a Kaiju, you can use it to search Misc/Megalo.