for the nendroid, the ball on his neck is supposed to go inside the head piece, that's how his head stays up. Since it's not a real one it may not fit in there but that's how it's supposed to be!
I love that sitting figure! I have recently been reading the chainsaw man manga and would love to get one of those for myself! Is there any type item code for it? I looked it up on temu and could not find it, thank you!