Blood Demon Sword Emperor

(Multiple female leads, special constitutions!)

Since you're using me to avoid an arranged marriage, it isn't unreasonable for me to use your body to improve my cultivation, is it?

A young man enters a sect to improve his cultivation after his mother is captured.

By chance, he obtains an invincible sword technique.

One sword rises, one sword falls, leaving no trace.

He rises to power and rescues his mother.