flame breathing is unlocked by talking to Rengoku at the mountain peak and doing his quest:
collect 20 demon horns (obtained by slaying demons)
and a demon collar (obtained by killing the axe demon)
Passive: when you breath your sword becomes engulfed in flames and deals burn damage to anybody hit by it.
first skill: unknowing fire: the user dashes at the opponent slashing them, also deals burn.
second skill: rising scorching sun: the user slashes their sword upward dealing burn damage.
third skill flame bend: shoot a ranged fire slash
fourth skill: blooming flame undulation: you swing your blade in a circle dealing damage to anything around you. (its a counter skill)
fifth skill: flaming tiger : you lunge and your flames take the shape of a tiger does good damage.
6th skill: RENGOKU: you charge up ready for a devastating slash, your flames take shape of a dragon dealing OP damage.
(only available to people with the rengoku clan/family)
-couldnt find any other footage for the techniques since some have already been used if you do have footage pls put it here