Demon Slayer: Kimetsu no Yaiba is a popular manga series that follows Tanjiro Kamado, who seeks to become a demon slayer after his family is slaughtered and his sister, Nezuko, is turned into a demon. The series is known for its intense battles and character development, and it has gained a large fanbase. While the specific number of characters in the series is not detailed in the results, it is noted that the manga features a diverse cast of characters, including demons and other allies, which contributes to its popularity and depth.