A question about drawings

[Virginia]

Hi you all!
I am a newbie in terms of Manga. Even if in my childhood I grew up with several Anime.
I have just finished Death Note series. And now a questions has came up into my mind.

Why Japanese/Oriental illustrators use the same graphical codes?
I could count up to 20 Light Yagami twins, with very few differences, if I think about the Anime that I saw in the past.
Same sensation when I see a shelf of manga in a library.

They are very full of imagination, so... why everything is so stereotyped? From the characters to their emotions.

Is it a cultural/philosophical consequences of what?
What do you know about it? Do you know any documentary about it?

If you don't understand my surprise, you can consider Diabolik, Peanuts, Corto Maltese, Milo Manara as very different examples of comics.

Thank you for your answers!

[Sérgio]

I know this thread is very, very old but it's a pretty interesting question.

I've been thinking about it and I don't think it's about ( lack of) creativity. If you explore various genres beyond kid-oriented styles you'll see a multitude of styles. The problem is with mainstream manga , and I guess I can come up with some reasons for this.

1) the manga market is dominated by very few companies (Kodansha, Shogakugan, ... ) so that helps to homogenize the visual style especially because the editors are very hands-on in all the creative process.

2) because of the use of assistants to produce a humungous amount of pages it's must easier to get a team up and running if everyone comes from a similar place in terms of drawing style.

So, in my opinion, it's not so much about their culture as it is about the main corporations restricting somewhat the styles accepted in the mainstream. ( If you think about superhero comics that happens as well with Marvel and DC)

Ps: Also Osamu Tezuka. He's such a big influence from the 50s onwards that it ends up reflecting in so much manga. I don't think there's a country where a single cartoonist is as influential as him