@ngungbi , I'm just some rando with an opinion, take it for what it's worth.
I think "Shrine Maiden" emphasizes that the kind of priestess is culturally Japanese or otherwise Asian ("priestess" feels like it'd be used more in monotheism with churches and the like), but either is fine.
As for Captain/Leader; use "Captain" when someone is directly addressing the person in question. When someone is describing that person, captain and leader can be used interchangeably (e.g. "He is our captain" or "The captain is the leader of our group").
If anyone disagrees I'd love to know why.