So at the start she was dying because of a paranormal infection, is it the same with him? Only he didn't get saved, he died and was reborn as something else?
I remember reading the webnovel I think of this, they skipped a lot of the early stuff she did as a kid to set up the future and I think this manga adaptation is likely to suffer as a result.
If that poor ugly girl was forced into a death game then that's pretty sad for her. She probably chose her victim as someone horrible she wouldn't feel guilty killing off. But her opponent was too strong. Tragic.