it says that yuri kept switching to doll and human is because his soul is unstable. the only way to prevent him from dying is to stabilize his soul, and the only way to do that is to merge all of his fragments into one, restoring him to his original state, and then return to mikael’s world. then by the end he shouldn’t be transformed into a doll anymore, no? then why is it still happening? someone please enlighten my shallow mind.
Same, when I saw that one panel where yuri turned back into a doll I just thought "Oh it must've been some memory before his soul got stabilised type sh" not really clearing the whole thing but that was just my opinion :3
Its bcz when yuri was experimented on, it made his soul unstabilize which caused a side effect and made him occasionally turn into a doll, hope this helps!
this is basically dante harem, everybody wants him (me included)