Hwarang

augh a drop from me

I think one of the leads is part of the hwarang and we see some other minor characters who are in it too

Mishil is a wonhwa, which the fan translation notes for this say is a female leader of the hwarang. Please note, that wikipedia makes no mention of this role, but instead mentions that wonhwa was a discipleship of women that predated the hwarang. It also mentions that there just isn't a lot of well documented history around the wonhwa or the hwarang. Really love the drama's interpretation of wonhwa being warriors though.