You will need a working visa to work as an IT/software engineer in Japan. There are three possible visa options: Engineer/Specialist in Humanities/International Services visa, Highly-Skilled Foreign Professional visa, and Working Holiday visa.
Engineer/Specialist in Humanities/International Services visa
The Engineer/Humanities visa is the most common visa for IT professionals in Japan who do not traditionally come from an IT background or related academic programs.
We’ll break it down in this simple scenario for you: You are an English teacher in Japan with a working visa sponsorship from the school. You’ve enrolled in intensive IT boot camps and found yourself an offer to work as a backend engineer. Immigration does not prohibit you from changing jobs even if your academic and professional experience is unrelated. If you have this visa, you can work as an IT professional regardless of how you originally got it.
Highly-Skilled Foreign Professional Visa
This visa has a unique point-based system that you need to accumulate through JLPT, salary, academic background, and professional experience (among other things). To be eligible, you need to have 70 points.
Different criteria give different points to the overall calculation. Holder of a Masters (20 points) and Bachelors degree (10 points) at a Japanese university (10 points) will need to acquire 30 more points. If you are below 29 years old (15 points) who hold an N1 JLPT certificate (15 points), then congratulations—you are now eligible for the Highly-Skilled Foreign Professional visa!
Working Holiday Visa
To be eligible for a Working Holiday visa, you need to be a citizen of the approved countries that hold an agreement with Japan such as Australia, Canada, Canada, the UK, and Germany. You are not technically allowed to accept a job offer, but it is an excellent option for entry-level IT professionals. After the visa expires (12 months), you will need to change your visa status or a company that can sponsor a normal working visa.