The four demon subordinates could simply hail from four different nations and cultures.
And Helen simply changes clothes. You can see her, wearing the same clothes as the rest of the maidservants, in chapter 1. And see her finishing changing at the start of this chapter.
This is operating on the assumption that either the investigators are incompetent or the royal family deems the Princess expendable, neither of which is a safe bet.
The kidnapping and killing of a Princess is a Big Deal. It's not something ordinary bandits would normally do unless they have...
Yeah, my interpretation is that Dartel is a human who roleplays as Belial, the Leader of Darkness of the Noble Demon Race, because he's a skilled Beast Tamer who commands demon beasts. Basically like how that kid roleplays as a some sort of a Pokémon Master.
They've never actually tried to switch back so the problem isn't that they had no idea how to switch back. The problem is Megumi refuses to switch back.
This is pretty funny. Like gee, I wonder why somebody would rethink their choices and relationships when faced with potentially devastating life changes. No duh it's not a coincidence. It really doesn't need paragraphs of fanfiction to explain.
@AlmondMagnum
Demonstrably, this one member became an army-destroying master-swordsman who thrived for 70 years, so perhaps the group simply don't really need many members to do whatever they want to do.