she might be much more obsessed in defeating the demon lord far than achieving world peace
(NO Spoilers ahead) Considering the fact that the Demon Lord:
1. probably killed her father and many other people ~10 years ago,
2. sent an assassin in Namari (the Gunner) without the intention of killing them,
3. made Yuuto's (probably) dominant hand unusable because he felt like it,
4. said he would leave them alone for the time being but instead "attacked" them just because he didn't like what he had for dinner,
5. openly shows his distain towards the party and (maybe because he)
6. speaks in a very condescending and rude tone (which I can't properly localize)
- is why I think that Hijiri considers him a very dangerous person who must be eliminated as soon as possible.