Zenitsu agatsuma

Zenitsu is a young man of average height with fair skin and downward-sloped, worried-looking eyes that fade from soft brown to gold and golden, forked eyebrows that sharply fade into a warm orange color. He has short, yellow hair of varying lengths, cutting off squarely at the ends where it fades to a darker orange color, that falls in front of his face in uneven bangs, loosely resembling a bowl cut. Before he became a Demon Slayer, Zenitsu's hair was originally black, but it turned the color it is currently when he was struck by lightning during his training.[2]

For some time following the battle at Mount Natagumo, his limbs temporarily shrunk due to Son's poison but were able to return to normal afterward thanks to medicine he had taken developed by Shinobu Kocho.[4]

He wears a paler brown version of the standard Demon Slayer uniform, which consists of a dark brown gakuran jacket, a white belt around his waist and hakama pants that extend, as well as his signature white-triangle patterned, yellow and orange gradient haori. As well as this, Zenitsu also sports a pair of Kyahan, tied at the front in 3 white bows, with the same pattern as his haori, pale brown tabi socks and white-laced zōri. Zenitsu is cowardly, weak-willed, and anxious, often claiming that he doesn't have long to live due to the dangerous job of being a Demon Slayer. He has rather low self-esteem despite his talent and strength, even considering himself useless, evident when he couldn't believe he had slain a demon and tricked himself into instead believing that it was Shoichi, even though the latter was a young child who didn't possess any form of skill.[5] Zenitsu is in a constant state of fear and he frequently tries to run away at the sight of danger, claiming he wants to live a modest, normal life, instead of that of a Demon Slayer. Due to this, Zenitsu screams and shouts a lot, much to the annoyance of the people around him. He is also shown to be pessimistic at times, especially during Hashira Training where he lashed out at Tanjiro and Inosuke for viewing the training positively.

In spite of his weaknesses, Zenitsu desires to live up to the expectations others have set for him and will try his hardest when he needs to. He holds great respect and admiration towards his comrades and his deceased teacher, Jigoro Kuwajima, and his inner focus and drive in avenging him help to wash away his cowardice and second thoughts when he is in a pinch. Zenitsu also hates himself for how cowardly and incompetent he is, genuinely striving to better himself. Zenitsu is also shown to be something of a wannabe womanizer, stemming from a desire to not be single should he be killed. He tends to hit on girls who he thinks are cute and asks them to marry him, much to their annoyance.[6] This womanizing nature is shown to override his docile and quiet personality, particularly when he believes his comrades are "flirting" with cute girls; he would snap and goes in long hysterical rants and complaints. Zenitsu is shown to have a strong attraction to Nezuko, openly expressing his affection for her and always rushing to protect her as if on instinct. During these times, he is also shown to become physically aggressive, lashing out at people in frustration.[7] Though, despite his shallow behaviour in this regard, Zenitsu does show to respect women, telling Daki to let go of a girl that Daki nearly tore the ear off of, and later demanded that she apologize, showing no fear at all in front of the enraged Upper Rank demon.

In spite of his cowardly demeanour and somewhat pathetic attempts to gain the attention of women, he has shown level-headedness in the rare occasion, becoming annoyed by his comrades' shenanigans, such as Tanjiro's kind naivety, Inosuke's bombastic personality, Kyojuro's boisterous and loud character, and Tengen's self-glorifying proclamations. As such, he typically squabbles with Inosuke when the latter goes on his loud demands and boasts. Additionally, as the only one to have grown up in the city, Zenitsu is the most street-smart of the trio, being the most familiar with urban environments and Japan's industrialization. As such, he became frustrated with his partners' lack of understanding, namely Tanjiro and Inosuke's inability to recognize a train.