Warning: This article contains spoilers for the Kimetsu no Yaiba anime episode 12 season 2.
Favorite character in Kimetsu no Yaiba, Thunder-Breather, Zenitsu Agatsuma captures the attention of many viewers as he sleeps. Zenitsu is confused between two states, a coward and a raging tyrant when he’s awake, but at least he tries very hard to separate the two. As Tanjiro Kamado’s companion and close friend, Zenitsu is also dedicated to saving the demon slayer’s life. Although he often fails to stay awake against demons, when he does fall asleep, he tends to leave traces of demons that have been wiped out when he wakes up.
A user of Thunder-Breathing, one of the five main Breathing Styles used in Kimetsu no Yaiba, the explosive technique of Zenitsu, Thunderclap, and Flash, will destroy the demons in a flash. However, Zenitsu can only use Thunder-Breathing properly while sleeping. This would be inconvenient for demon slayers, but for Zenitsu it might be an advantage, he could just fall asleep in the middle of a battle.
As for why Zenitsu often fell asleep in the middle of a deadly and bloody battle, the answer was simple: he was too scared. Most of Muzan’s demons are monstrously transformed and all have tremendous power. To be fair, Zenitsu is rather cowardly, so he’d be more terrifying than Tanjiro and Inosuke. Although it sounds scary to sleep, it’s quite odd.
Zenitsu is calm and crouched in his sleep, acting with extreme precision. The character is a far cry from someone who screams and screams about anything when sober. However, behind his eccentric and sometimes offensive behaviors, Zenitsu has problems with low self-esteem. He knew he was a coward, but he couldn’t change it. His low self-esteem makes him weaker and more cowardly.
On the positive side of the story, Zenitsu seems to be on a path to self-improvement. At the moment, the anime is at the height of the Entertainment District arc and Zenitsu is showing his fear of demons, but not as much as before. He doesn’t whine about single quests and even stands on a par with Daki. Zenitsu would still use Thunder-Breathing for sure, but at least he wasn’t as scared to faint as before.