A journey of a young dectetive

A girl Keiko travels back in time with powers to see a politician being murdered she decided to solve it but something happens to the girl which makes her a hero.

Then soon gets betrayed by her friend and then Keiko soon finds someone who can help her and they both try to solve the mystery, but then something both happens to them and they fade into a new realm. Where they both find that the city they lived was gone and soon find a way out of that realm.

Finally, some years pass by and something to Keiko while she was in labour and she passes away but the story continues from her son's perspective as another murder strikes again.