Harry Potter: Voldemort and I Were Schoolmates

[Original Female Lead + Pocket Dimension + No System + Golden Finger]

[Sorry if anyone acts out of character (>_<)]

Bad news: She's dead. Good news: She's transmigrated.

A car accident sends Mu Bai to another world. She thinks she has transmigrated to Britain during World War II, in the era of the Great Depression.

Then she discovers she's transmigrated into a novel she read in middle school: Harry Potter, written by J. K. Rowling.

But if she had to transmigrate, why did she end up in the timeline when Voldemort was still a child?