Basically, it's a story about a righteous heroine and an evil one roaming the martial world, overcoming challenges and growing stronger, with a little romance along the way.
She's the disciple of the greatest martial artist in the world. She's the Demon Cult leader everyone wants dead. In this martial world where neither of them can control their own fate, what will become of them?
Well, actually, it's a story about a calculating schemer who treats doing good deeds as a job, has no sincerity whatsoever, and just wants to slack off, paired with an exemplary righteous student, and a Demon Cult leader who's new to the world and doesn't know how cruel people can be, can take on ten people at once, finds everything too much trouble to think about, can't make sense of anything, and, once she falls in love, only wants to enjoy a proper romance.