Demon Slayer: Season 4 - Episode 3 (Patreon)

I've really enjoyed the past two eps. Can someone clear up, which upper demons did they defeat last arc, 5 and 4 right? Why is this eye here bruh!!! (please no manga spoilers)

TENGEN SLIDE TANJIRO ONE OF YO WIVES

I wonder what would be slid in to add a bit of spice to the training periods, I figured we'd get some time to dive into some of the other Hashiras within this season too but I wonder how that'll make the arc feel as a whole by the end