that last page, Is that Asta's devil in human form? or is that Asta? but it doesn't look like him, well idk
I think it's the devil that starting to look like Asta. In exchange of his body parts to gain some temporary power I guess, in order to save Yami.
that last page, Is that Asta's devil in human form? or is that Asta? but it doesn't look like him, well idk