Muichiro is an easily distracted person who can't seem to concentrate on anything and seems to be lost in contemplation all the time. He is impassive and occasionally obtuse, thinking only for himself and acting solely on reason, never allowing emotions to influence him, giving the impression that he is apathetic and uncaring. But Tanjiro Kamado could tell that Muichiro wasn't intentionally cold, because he didn't give out any hate.

Despite his generally carefree and indifferent manner, he has demonstrated the ability to become serious when necessary and is committed to his role as Mist Hashira of the Demon Slayer Corps. On the other hand, he seems to have a cold and haughty side. This is demonstrated by the way he angrily shakes down Kotetsu and calls him foolish, claiming that his time as a Hashira was more significant than his own and that the swordsmiths' only job was to create weapons. Despite this, Muichiro appears to have a great deal of respect for Kagaya Ubuyashiki, which is probably why he doesn't seem indifferent to him.