She said she mutilates herself further every time she kills someone, so healing her would be an exercise in futility.
Also, though this is just a personal opinion, Rushia may be keeping that one mess as a sick, painful mark of sorts, something that constantly reminds her of her ordeal and fuels her self-loathing.
I dropped this a few years ago, it crossed my mind today and what do you know, fresh translations after 3 years. Thanks for the chapter, though ai'll be restarting from the beginning haha.
What kind of backstory did Mine have to prompt her to rape Rushia after hearing all that? It's been ages since the updates and I forgot what her deal was.