Webit's revealed that nakime has replaced hantengu as the new upper rank four and that kaigaku (a former demon slayer and senior to zenitsu agatsuma) became the new. His fighting skills and training as a. Webkaigaku is one of the supporting antagonists in the infinity castle arc in demon slayer. Originally, kaigaku was a demon slayer who was a disciple under the. Webzenitsu agatsuma vs kaigaku is a battle that took place in the infinity castle. It focuses on the battle between demon slayer zenitsu agatsuma against upper rank six kaigaku. Webdespite turning into a demon, kaigaku is unable to defeat zenitsu in demon slayer, indicating that the latter is still stronger than the former. Webkaigaku, initially a demon slayer turned demon, rises to the position of upper rank six within the twelve kizuki, a group of powerful demons serving muzan kibutsuji. Webkaigaku's betrayal led to gyomei's imprisonment and jigoro kuwajima's death, fueling zenitsu's rivalry. Kaigaku became upper rank six of the twelve kizuki,. Webi've seen plenty of discussion about why kaigaku was upper moon 6 instead of 5 and the most common answer seemed to be that he wasn't strong enough for number 5.
