I have a feeling we made a mistake by freeing the Kirishima priestess. I'm just predicting that she's going to cause trouble for our squad.
But regarding the "tomb" in any case:
- if it melts like Reimu's evil magic, then it definitely needs to be melted;
- if you find a girl kidnapped by an evil villain and can free her, then you definitely need to free her;
- it could be Kirishima, or a completely random girl - a princess, a servant, someone's mother, there is no reason not to free her;
- if it's a priestess, then she may have turned a good king into an evil heretic, but that still doesn't negate what he did, or his weak character;
- if it's a super evil priestess, then several hundred years spent in the ice could still have somehow influenced her worldview for the better.
In short, 10/10 would liberate again.