@Bored-chan it probably is that girl who ordered mc and all before mc returned, while he was part of the demonic sect and the person who mc called as "master" I believe..
Spoiler text. He is the twin of the sword saints granddaughter who eventually became the head of the demonic cult and MCs master in the original timeline.
I think they got opposite powers which why the girl was OP in the manhwa beginning.
His mom ( the sword saints daughter) got lost in an alternate evil dimension which is why the sword saint quit being the leader of murim bc the entire team sent was annihilated and that Mt Hua woman got injured over there also.
MCs dad was also in the team and a whole bunch of strong pple but they lost hard.
The alternate evil dimension is where the MCs power is from but its kind of parasitic.. he can prey on other demons type sh**.
I mean can't exactly call them twins plus even in the novel we don't know much about this just that the blood demons daughter was the heavenly demon and the divine sword was a part of the heavenly demon previously but something happened during the abyss incident.