Zenitsu Agatsuma vs Kaigaku is a battle that took place in Infinity Castle. It focuses on the battle between Zenitsu Agatsuma and Kaigaku.
Zenitsu runs upon his former elder, Kaigaku, who he hears chatting behind a closed door while walking through the castle. He orders the Demon to leave since he recognises him. Zenitsu’s rudeness irritates Kaigaku, who informs him that’s not the way to talk to his boss.
Zenitsu responds that, as a Demon, he no longer regards Kaigaku as his superior.
Kaigaku sneers at Zenitsu, saying him he’s a wuss, then tries to irritate him by questioning whether he’s become a Hashira or if he can utilise anything other than the first form via Thunder Breathing.
Despite the fact that he is only filling an empty position, Zenitsu calmly retorts that Kaigaku appears to be happy to be the lowest rated High Ranks.
Zenitsu shames and reminds Kaigaku that he is only a replacement for the High Ranks.
Kaigaku smiles and says he now understands how to respond to Zenitsu’s slur. Zenitsu is curious as to why Kaigaku became a demon, given that he was formerly someone who was passionate about studying Thunder Breathing and aspired to succeed Thunder Hashira. He vents his frustrations to Kaigaku by informing him that he is to blame for Jigoro’s death, as Kaigaku became a Demon after committing seppuku and dying a slow, agonising death. Kaigaku mocks Jigoro, calling him a senile old man, and adds that only those who recognise his worth are worth caring about. Zenitsu looks down his nose at this.
Zenitsu’s comment towards Kaigaku angers him, and he tells Zenitsu not to put him in the same basket as him. He draws his blade and engages in combat.
Kaigaku uses his upgraded Blood Demon Art Thunder Breathing, Fourth Form to try to kill Zenitsu. Zenitsu, being as quick as he is, draws his sword and cuts Kaigaku’s neck, calling him garbage and claiming he was too slow. Zenitsu is far more adaptable and proficient in swordsmanship than previously, Kaigaku recognises. He remains confident, though, that no matter how hard Zenitsu trains, he will never be able to defeat a Higher Rank. Kaigaku then uses the Thunder Breath, Second Form: Spirit of Rice on Zenitsu. When Zenitsu notices Kaigaku has eaten too many people, he wonders whether he can’t differentiate right from wrong, to which Kaigaku proudly replies that he can.
Kaigaku states those who assess him rightly and accept him for who he is are right, while those who do not accept him are wrong, as he uses Thunder Breath, Third Form: Thunder Swarm. Kaigaku then teases Zenitsu with Thunder Breath, Fifth Form: Heat Lightning, while complimenting his own upgraded Blood Demon forms. As he employs the sixth thunder breath forms, Rumble and Flash, he adds that once his thunder breath forms slice Zenitsu’s body, his skin and flesh would burn and split. While falling, Zenitsu considers his previous relationship with Kaigaku and concludes that he and Kaigaku will never get along. He leaps onto a wall and breathes normally: Honoikazuchi no Kami, Thunder Breathing, Seventh Form
The aftermath of the fight
Yushiro saves Zenitsu while he is falling. Yushiro mocks Kaigaku by informing him that dying alone is no pleasure. Zenitsu is saved when Kaigaku dies.