Talk:Twelve Kizuki/@comment-33959269-20191014160711/@comment-269409-20191104223856

The Lower Moons aren't necessarily weak, per say, they just aren't highest tier in the verse. They would kill most other slayers (refer to Rui's anime flashback where he slices up all those men effortlessly. Tanjiro had to work hard to fight Kyogai and Rui as well, before he could fight on a Pillar's level). Muzan was just annoyed that they weren't strong enough for Pillars and that he kept replacing them because of it.

As for the Lower Moons becoming Upper Moons, unlikely. Enmu mentioned the disparity in strength between an Upper to Lower Moon before dying and how even after receiving more blood that he wasn't even close to it. Enmu couldn't do it, and the others would surely fail as well.