Today, I've finished reading the comics of NausicaNausicaa of the Valley of the Wind manga.

Some other options:
Today, I finished reading the Nausicaa of the Valley of the Wind comics.
Today, I finished reading the Nausicaa comics.

I ultimately chose to use "manga" instead of comics, because English speakers tend to call comics from Japan manga, and comics from Western countries comics. I think for an online audience, who is relatively up to date with recent trends, manga might be the preferred word. But if I was writing for an older audience, I might use comics. I also think it is better to give the full name of a work the first time you talk about it in a text, and then use the shortened form after. However, I think it's annoying to have to research the English name for works, so it is also fine to just call it Nausicaa.

The comics are split across seven volumes and I thought toI would read one comicvolume a day, but I read all of them today because they are really fascinating.

Mostly a correction to make it a bit more smooth sounding in English.

Before reading, I've watched the movie of Nausicaa movie, so I was surprised that the stories are so different.

I think you occasionally use "I've" when you don't need it. Using "I have" makes an action into the present perfect tense. This means the action has a link from the past to present, and cannot be tied to a specific time. This is not necessary when you are just describing things that happened in the past. (If you want more information on the present perfect tense: https://www.ef-australia.com.au/english-resources/english-grammar/present-perfect/)

I could understand the world view, which is elaborated and complicated.

I knew Hayao Miyazaki is a genius, not only foras a film director but also as a manga artist.