Although the first part of the Demon Slayer: Infinity Castle trilogy has made its debut in Japan, global fans still have to wait a few more weeks. Fans in the U.S. should mark their calendars as the film will hit the theaters on September 12th, 2025. Among the many characters who have been getting fans’ attention since the teaser was released, the one who surprised us the most is Zenitsu Agatsuma. The once loud and cowardly Demon Slayerwho will always whine about fighting demons, is staring straight at one of them with a menacing look. Zenitsu’s entire demeanor changed during the final stage of the Hashira Training, and the Infinity Castle Arc will finally explain why.
Even as someone who never really liked fighting, Zenitsu always had a lot of potential. However, he only knew how to use the first form of the Thunder Breathing Style. He was taught by the former Thunder Hashira, Jigoro Kuwajima, whom he regarded as his grandfather. Moreover, Zenitsu likely didn’t realize the true extent of his capabilities since he would always pass out in fear. Most of the fights he has won so far were through his subconscious mind, and he will often wake up surprised after defeating a demon. However, things will be entirely different in the final arc.
Warning: This article contains spoilers from the Demon Slayer manga!
Zenitsu Taps Into His True Potential in Demon Slayer: Infinity Castle
Knowing only one form of the Thunder Breathing Style never got in Zenitsu’s way since he mastered it to perfection and used it at its maximum potential. The Thunder Breathing Style has a total of Six Forms, and Zenitsu will never learn anything besides the first. However, he achieves something only a select few Demon Slayers have done: creating his own unique form. During the Infinity Castle Arc, Zenitsu fought Kaigaku, who was also a pupil of the former Thunder Hashira.
Kaigaku chose to become a demon, which led to Jigoro committing Seppuku. Zenitsu learned of his master’s death during the final stage of the Hashira Training, which strengthened his resolve to kill Kaigaku, who had recently been promoted to an Upper Moon Six. He even went into the Infinity Castle without panicking. The fight between them is brief, and Zenitsu wins only because he uses a seventh form of Thunder Breathing. Since the criteria for becoming a Hashira are to either kill 50 demons or one of the Twelve Kizuki.
While the series never explicitly said how many demons Zeinitsu has killed in total, he did fulfill the requirement by killing Kaigaku. However, since the series had already ended and all demons were dead, there was no need for the Demon Slayer Corps to continue. Therefore, despite having the qualifications for becoming a Hashira, Zenitsu never gained the title since the battle’s conclusion meant a peaceful era would begin without the terror of the demons.
