Software development in Japan is decades behind the US and other parts of the world. You also won't be making that good of a salary, which won't go far if you are living in a big city like Tokyo.

My guess is that you need this for the work visa.

It would be better to get a remote US job and find some other way to get a Visa.

As a software engineer in Japan... yes there are jobs here that don't require Japanese, but you'll be limited in both job- and daily-life-opportunity without it. Cool that you are learning it. I came here with zero Japanese. Now I use only Japanese all day every day at work.

Software (as well as all other industry) salaries here are pretty low, though outside of big cities, so is the cost of living.

First step, you definitely need a "COE" which is essentially your first work visa, sponsored by an employer. Once you get that one and are in Japan, it's pretty easy to switch companies.

I dunno how easy it is to do these days, but lots of people used to come and teach at "English Conversation Schools" for peanuts, with no experience. They get an "Engineer / Specialist in Humanities / International Services" visa, which is kind of a catch all for the kind of work you can do. Once they're in, with this visa, and about a years' work, switch to a industry and role that better fits them.

Note: remote, or even hybrid positions are less common here than "in the west."