Unless you're freelancing, and the animation company is outsourcing for things like background painting and filling in the animation between key frames, you're extremely unlikely to find work with a Japanese animation company as a westerner. There are also very high language requirements, as communication between team members is essential when working in animation, to ensure everyone knows that the exactly what look and tone is being sought with every scene.
I hate to be a wet blanket, but this is just reality. To ignore it and fantasise regardless is to set oneself up for disappointment, but if you acknowledge it, you can set in motion plans to overcome it or work around it. You just need to accept that it may take many years.
If you're serious about working in animation, you should start by looking to land a job with small animation studios in your own country. And in order to do that, you'll need to study quite intensively to meet their skill requirements.
That's not how this works. Your skills already have to be of a professional standard in order to be hired, even by small studios. Studios don't just hire a rookie and hope their art improves, they hire people whose art is already brilliant. That's what you should be focusing on. That doesn't have to mean art school - you can be self-taught, and study by yourself online - but you need to treat it like art school and truly focus on the 'boring' things like figure drawing, perspective rules, composition and so-on for a while. There are great online courses which can really help. You want to avoid anything anime-focused, and go for courses which focus on the fundamentals of landscape drawing/painting and the human figure.
Once you have a foot in the door of the animation industry, and you have experience, you stand a much better chance of being hired in Japan. But you should absolutely focus on the animation industry in your own country first.
Again, I don't say any of this to be mean, or to upset you. There are ways into the industry you want to work in. It's possible. But it'll be really, really hard, and it'll take a long time, and you absolutely have to be at a professional level first. If you can master your fundamentals and reach that professional level through proper, self-motivated study, which you can probably do if you study from home full-time for a couple of years, you'll be equipped to start looking for entry level animation jobs.
By recognising and acknowledging the hurdles, and working to overcome them, you're far closer to making your dream a reality. Even if reality is far harder than our fantasies. 
