If one has come up with an anime manuscript, where or who should you write to if you want to know if the idea is of interest and actually could become something? Or would it be made as a manga first?
Also, can you like "patent" the manuscript, so that if it actually would be of interest to someone, they don't just change half of the content if they felt like it?
First of all, I doubt they'd look at any scripts not written in Japanese. Second of all, I'm rather doubtful you'd have much success simply pitching an idea to a studio as a person outside the industry. There are, however, many venues to get an idea made into an anime, eventually, but these venues require the person who came up with the idea to produce something.
I'm of course talking about creating some sort of light novel, manga, or comic on your own. These things don't even need to be backed by any sort of publishing company. Japan has thriving communities for posting this sort of original creative works online, such as Pixiv. There are quite a few shows now that started life this way: Wotaku ni Koi wa Muzukashii and Rise of a Shield Hero, to name a couple.
If Japan's TV industry is anything like America's, they are mostly disinterested in ideas. Ideas are a dime a dozen and can be made or broken by their execution. They are much more interested in some sort of proof of concept that the idea will be successful.
As for preventing changes to your idea, you'd have to make sure to put that in any sort of contract you sign to give them permission to use your work. I would guess that would be extremely difficult to pull off unless your work is proven and popular, such that you have enough power by popularity that your idea is good without changes. I feel like worrying about this though is putting the cart before the horse.
An article on Anime News Network titled "How do I get my idea made into an anime?" should be a good read, at least for me it is, which does not pull any punches on delivering the reality of the anime industry in general. This gave me a general idea of how things really work. Before worrying about whether your ideas will be changed or not, you should worry about whether or not you can even pitch it to studios or something.
The article above mainly revolves on one point: nobody cares about your ideas. This might be quite rude or something for you but according to the author, who is the founder of Anime News Network, ideas are abundant in the industry. It is a business, so what they care about is what the public wants, so if your idea doesn't fit the current trend, then it will most likely not see the light of day.
In addition, to quote from the article,
...even if you are a creative genius, the door to creating an anime is simply not open to you, for several reasons.
- You don't speak Japanese.
- Nobody knows who you are.
- You have no market strategy.
These are the three main things you should worry about. Of course, as stated in the other answer, you can post your original work online in order to gain audience and popularity. But, you should understand that it is not as easy as you think. So, before worrying about whether you need to make it manga first or whether your original idea won't be changed, try to worry on how to make anime studios see that your idea is worth even becoming an anime at all.
I agree with Kai and W. Are's answers and while their answers outline why you should not get your hopes up, I'd like to highlight a few examples of animes that show that this isn't necessarily impossible.
First up are Heroman and The Reflection. Looking at the writers, you'll notice that they were both written by Stan Lee, creator of many well known Marvel comics.
As a second method, I'll bring up Neo Yokio, an anime that was harshly criticized but shows another possibility: Netflix. Netflix has been investing a lot of money into not just getting animes on its platform, but producing them as well. This one was created by the lead singer of a band, but I'd like to think that Netflix could open up the possibility of Western people getting more involved with Japanese studios.
Finally, you can make your manga and hope it takes off. As Kai mentioned, they have hundreds, probably thousands of ideas they can consider. Outside of being in the industry (and having shown success), the only real way to get your ideas turned into an anime is by your idea being a success beforehand.
Some examples in this last category include Radiant, Howl's Moving Castle, and Tales from Earthsea. Do note, however, that in the case of the Earthsea, it was changed enough, for Earthsea's author to not really consider it her story anymore.
This brings us to Radiant. This is a comic that takes a lot of inspiration from manga and thanks to the artist of One Punch Man, it got picked to become a part of the Euromanga Collection. A safe assumption may be that this became an anime thanks to having presumed success in Japan.
I think what this all shows is that it's not about having a good idea, but like W. Are said, giving the studio a reason for them to make it in the first place. And as my examples show, this reason could be you being a person of large influence, getting the right connections or your idea having success in its medium (whether a comic, novel, or perhaps some game).
I wouldn't get your hopes up with just the manuscript/idea, but do know that it's not outside the realm of possibilities for your work to get an anime adaptation.
