Can only one person become the chief? And I know that there can be only one chief (at least at a time), but is only one of the villagers able to put on the mystic robe?

And, I suppose as a follow-up question, what happens when/if the chief dies, if that is even possible.

To expand a bit on the answer, the robe will "fit" only one villager - the one chosen to be chief, and it's your job to find that chosen one. The chief is mortal, just like any other villager, and when the chief dies, another is chosen to become the chief (and, once again, you must find that chosen one).

Actually... I got this strange pop up orange boxy thing (don't know the technical term sorry) and it said my chief had found some sort of crystal when he was out walking, it made him happy and it seemed slightly familiar. It asked me whether he should keep it or throw it away, so I kept it and it said he became really clam and gradually realized someone else was holding onto it as well and that he was surprised to notice the person looked exactly like him. So basically he got a twin, and he had on the same robe as the chief though his twin doesn't have chieftain powers.

That is actually a small design flaw in that Island Event (Crystal of Reflections). The chief probably should not be the subject of that event, since there can be only one chief.

i had that same one except my chief was a old lady and right after wards both her and her twin died but i think thats more because she was 77 and not because of the event

OK. That's good to know because the first citizen I had try on the robe happened to be the chief, so it was a bit of a surprise and I had no idea if that was normal or just dumb luck. Thank you!