At the risk of assuming too much, it sounds like you might be a little confused as to what a work visa is. Work visas aren't issued just because someone has a source of income, but are issued specifically to allow a person to engage in a specific type of business activity within the country.
In broad terms, there are two criteria the authorities look at when evaluating work visa applications:
1. Can the person do the type of job they're applying for a visa for? Specifically, can they earn enough working in that field so that they can support themselves?
2. Does the person need to be in the country to do that job? Or, at the very least, will being in the country let them do the job better?
Generally, the answers to both of those has to be "yes" for the government to grant a visa. For your case, though, it sounds like right now the answer to Question 1 is "maybe," and the answer to question 2 is "no." As an "aspiring author," right now you're got no demonstrated past income from writing, nor guaranteed future earnings from it, and so, for immigration law purposes, you're not a professional artist, and if it's not your profession, you're unlikely to be granted a visa for it.
Even if you could convince the immigration bureau that you're a professional writer who can support himself through that line of work, you'll still have to answer the question of why you need to be in Japan in order to write. Is the subject of your writing Japan-related, and so living in the country will allow you to better research or understand things that will go into your writing? Are you publishing your book in Japan, and thus need to be in the country to better communicate and coordinate with Japanese publishers, distributors, etc.? If not, a work visa is going to be hard to come by.
「I won’t have a sponsor company in Japan but in America, and I would like to know if it is possible to get the Artist Visa with a sponsor company in america or just in a country other than Japan in general?」
It sounds like what you're asking is if it's possible for an American publisher (i.e. a publisher located in the U.S.) to be your sponsor for a Japanese work visa. That's very unlikely. Again, if the sponsoring company sees no benefit from you working in Japan, they're not going to want to go through the time and expense of the legal process of registering as your visa sponsor if they don't feel like you living in Japan is going to produce a better book/product. And again, even you do find an American publisher willing to register as your sponsor, the Japanese immigration bureau is unlikely to grant you a visa if they don't feel like you need to be in Japan to do your job.
I suppose it could be possible that an American publisher that also has operations in Japan (by which I mean an office and staff in Japan) could sponsor you, but in that case the visa would be sponsored by the publisher's Japanese branch, not its home U.S. division.