Anime movie with child abduction?

At some point, I saw a movie about kidnapping. In the end it was the class teacher and the protagonist was turned from adulthood into a child to save the girl who was abducted and killed. The boy knew that he had grown up before and it soon became clear to him that he must save the girl and therefore relive everything. The girl was abused by her parents and he has always tried to be a friend for her to protect her and prevent her from being alone and abducted on his birthday.

Unfortunately, I do not remember where I watched the movie, Netflix is, I do not think so, I did not find it. Maybe someone knows something.

Erased https://www.netflix.com/...e/80114225

Uff, right.

Detective Conan or Erased or etc.

Sounds like "Boku dake ga Inai Machi" aka "Erased: the city that does not exist".
https://www.anisearch.de/...inai-machi
But it is a series and not a movie.

But there's also a Realverfilmung (series), which runs on Netflix.
https://www.anisearch.de/...inai-machi

And a Realverfilmung (film).
https://www.anisearch.de/...inai-machi