There's an endless debate about the separate merits of anime and manga series, which makes it particularly interesting when an anime adaptation strays away from its complementary source material. By and large, anime adaptations use the original manga as a guided framework on how to tell their story. However, there's no hardened rule that anime must faithfully adapt their corresponding manga.
Source：https://www.cbr.com/anime-adaptations-not-like-the-manga/
