Demon Slayer: Kimetsu no Yaiba debuted its first season and became one of the most popular anime series of 2019, but went down as one of the most successful releases of the decade overall with a huge boost in manga sales to go alongside its anime. One of the biggest reasons behind the series' quick success were the various quirky characters that made their debut during its run. This undoubtedly includes the wacky Zenitsu Agatsuma, whose strange reasons for joining the Demon Slaying Corps in the first place made him a huge fan favorite.