Two female protagonists: a fierce and domineering female hero, and a sleazy time-traveling girl, although the latter one appeared very late...
In the name of romance, there does not necessarily have to be a male protagonist. Friendship and integrity are the key points.
It borrows some settings from Hunter, but it has little to do with the plot, so it can be viewed as original.
There are a lot of bad things, the lower limit is eye-catching, and overall it is really healing.
All of the above in an effort to save the world (dirt!)