Su Xiao was a college student who had just graduated in the 21st century. She accidentally drowned after jumping into the water to save a little girl who had fallen in. By rights, she wasn't meant to die even if she'd gone in after the girl, but she had the misfortune to run into a soul reaper who had just started the job. The girl she saved was the one who was supposed to die, but the reaper botched the job and took Su Xiao instead. All they had to do was return her soul to her body, but the girl's family, afraid of being sued, secretly found someone to cremate Su Xiao's body and hurriedly bury her. You could say she was a good person who got no reward for her kindness.
When she learned what had happened, her resentment exploded, causing upheaval throughout the Underworld. By the Underworld's rules, a vengeful ghost whose resentment runs wild should be suppressed immediately. If she still refuses to behave, then she should be beaten until her soul is destroyed.
But Su Xiao had died saving someone and was protected by merit. Her allotted lifespan had not yet run out, and the Underworld was at fault for taking the wrong soul in the first place. That made her a tough nut to crack. But if they did nothing and let her resentment keep growing, the Underworld wouldn't be able to take it. In the end, with Bodhisattva Ksitigarbha mediating, Su Xiao finally agreed to bind herself to a System and complete missions in other worlds, earning points to buy herself a new body with money and beauty.
As for which System to bind herself to, Su Xiao had this to say: good people get no reward, so she wanted the Wicked Empress System. She changed her name to Su Yaoyao and decided that in this life, she'd be thoroughly wicked. But the trainee soul reaper was seriously unreliable. Why could everyone else hear her thoughts after she bound herself to the System? She's a wicked empress who brings ruin to her country, not a fairy who saves the people and the realm!?!
