I Transmigrated, but This System Is Unreliable

Li Xi was an unremarkable office worker in the 21st century. After a car accident, she transmigrated to the Primordial World. Luckily, she activated a System, but after giving her a few magical treasures, the System vanished, explaining that Li Xi wasn't its Host. After waiting for hundreds of millions of years, Li Xi's personal System finally arrived, and took her across countless worlds. First world: Ye Luoli Second world: Douluo Dalu Third world: The Grave Robbers' Chronicles Fourth world: ...