Sun breathing should be reletively hard to get just not too hard. You should either have kamado clan(if that is gonna be a thing) or you should do quest on pve or pvp.
1st move: Sunbreathing/Hinokami kagura dance:
Where you fly foward doing a barrel roll and a slash doing burn damage. If you miss it you should do one more barrel roll towards the enemy.
2nd move: Sun breathing/ Hinokami kagura
Clear blue sky: you jump high in the air and you drop down doing a slash to the ground in a circle rotation also doing burn damage and aoe damage.
3rd move: Sunbreathing/Hinokami kagura Raging sun: you dash foward doing 2 slashes With flame imbued in the sword Cutting the enemy and sending them back.
4th move: Sunbreathing/Hinokami kagura Burning bones summer sun: You fly foward doing a barrel roll doing burn damage and if their low it should follow up with a sword slash downwards.
5th move: Sunbreathing/Hinokami kagura Setting sun: a Counter that flips you body over and slashes the head doing burn damage but not for long.
6th move: Sunbreathing/Hinokami kagura Solar heat haze: You stand still charging up putting your hands up charging you sword(its cancelable) and you flash step(again if thats a thing) and you slash downwards doing no burn damage.
7th move: Sunbreathing/Hinokami kagura Sun dragon halo dance: You dash backwards doing a quick charge up of sun halo dance and you fly in a flame Beam for 9 seconds stunning them.
8th move: Sunbreathing/Hinokami kagura Hinokami: (you have to be low hp to activate it) you run fowards with a flame sword(you should add the Hinokami music) and its a cinematic, im out of ideas for the the cinematic._.