Well you do know that Yuuki can just fly above him till he gets tired
1 is that in character for her to do so?
2 does she have ranged attacks?
3 she can mentally get tired making her attacks clumsy
4 rengoku is no stranger to opponents with infinite stamina, no one in the KNY verse is, they fight those in a regular basis
5 since speed is equalized, this is an easy blitz due to the breath styles's speed amps, he can just jump after her or blitz here before she can fly out of range
The hundreds of strikes are also a speed feat and if they are comparable then she can counter them easily as well, and the skill gap doesn't to be so big that she wouldnt be able to outlast him here.
which they're not, rangoku automatically has the speed advantabe due to breath amps
Not to mention she has broken regen,
saying she has broken regen is nothing but a funny joke in a verse where even mook demons regenerates entire limbs in less than a second, her regen is nowhere near the regenertion even mook demons have in KNY
Not to mention she has broken regen, like what is he gonna do? Yuuki can rush, sacrifice a body part strike him in a vital spot
..you mean the signature fighting style demons have in demon slayer?
did you like forget what kind of opponents rengoku fought his entire life?
he fought demons with broken regen and infinite stamina, the only difference here is yuuki can fly, he is way too used to opponents like her to begin with for her physiology to have any significant effects
and once again, is that in character?
did she ever use that kind of fighting style against literally anyone?
either ways, rengoku can just blitz with speed amps and cut her in half, he has the definite speed advantage, like i said