Arisunime — The battle between Zenitsu Agatsuma and Kaigaku inside the maze of Infinity Castle is an emotional clash between former close friends who are now on opposite sides, and is the climactic moment of tension in the arc. As Zenitsu steps through the castle’s ever-changing hallways, he hears the voice of Kaigaku-his former senior and fellow student-challenging him sarcastically. Kaigaku mocked Zenitsu for his fear and questioned him if he was truly evolving, while Zenitsu asserted that his priority now was to eradicate demons, not honor a senior who had betrayed the human path.
With a lightning-fast blast of the Thunder Breathing technique: First Form – Straight Thunder, Zenitsu opened fire on Kaigaku, but the demon launched an advanced form of the technique-Second Form: Rice Spirit-which scratched Zenitsu’s body and forced him to endure the pain. The battle then escalated as Kaigaku performed various forms of demon blood-enhanced thunder breathing, including Fourth Form: Distant Thunder, Third Form: Thunder Swarm, to Sixth Form: Rumble and Flash, demonstrating his mature power as an Upper Rank 6. Amidst the destruction he wreaked, Zenitsu remained stoic, channeling anger over the death of their teacher-Jigoro-which was largely due to Kaigaku’s betrayal.
At the climax of the battle, Zenitsu unleashes a move from his personal experiment: Seventh Form: Honoikazuchi no Kami, a technique Jigoro never taught him. The one-slash attack cut off Kaigaku’s head as they both fell into the chasm of Infinity Castle, signaling Zenitsu’s victory. While Kaigaku’s head was wrapped in curses and rage, Zenitsu was exhausted and unconscious, saved by Yushiro who appeared in time.
The essence of this duel is profound: Kaigaku who chooses the path of the devil for instant power, while Zenitsu develops through hard training and humane determination, showing that human superiority is not just about physical strength, but determination. In this short but slick play, the audience sees Zenitsu’s evolution from a comical character to a true hero-ready to face both the enemy and the shadows of his past. This is not just a physical battle, but a symbolization of the difference in values between betrayal and devotion.
The Zenitsu vs Kaigaku duel emphasizes Zenitsu’s character development from a weakling to a true Hashira, with strong emotional roots and a new signature technique-his success confirms that the path of a Demon Slayer is not about strength alone, but sacrifice, training, and the desire to grow.***
