Webtechnically, kokushibo is much more likely to be able to use sun breathing efficiently than muichiro, but he still uses moon breathing.
They just weren't born with bodies that.
Webmuichiro's body is predisposed towards mist breathing.
That's the only thing he can truly master.
Any other style, he could learn, in the same way that tanjiro's ancestors learned.
Webfrom character development to its impact on the story, this video breaks down the key aspects of sun breathing and its role in the demon slayer universe.
Webmuzan and kokushibo have a history of hunting down sun breathing users because of their experiences with yoriichi.
And a sun breathing user becoming strong enough to.