Side job tax

Hello. I am under humanities working visa for a Japanese company. I want to earn extra income from a side job but the main company will not approve of it. I have read here in one of the articles that if it is a cash in hand job then the tax office will not be aware of it. However, I have talked to friends and searched on the Internet, I found out a couple of problems in that. First, there are companies that pay the salary in cash but they also pay the tax so immediate possibility of getting caught and secondly, Residence tax or some kind of tax for which you have to pay 6 percent of your annual income so this is another way of getting caught. Could somebody please guide me on that?

i highly recommend you to not get paid " under the table".

if you get caught your visa can be on jeopardy.

sorry for the typo i meant to say " in jeopardy".

Thank you for your reply!!
I have another point to add. I had come here as a student in Japan and I was working in this company simultaneously as a part-timer. At that time I did not know about the intricacies of the Japanese system so without thinking much, I started another part-time job for which i was getting paid in a separate bank account. However, my main money did not have one bit of knowledge about it. I do not know the reason why i was not caught. On top of it i had also given the 2nd job `my number card` but my main even till today does not have my `my number card` . I was wondering whether this could be the only reason why I have been safe. I have had no problem in visa or tax whatsoever.
Could someone help me out on this because i am in real need of money?

First not knowing about the system is your responsibility and is not an excuses.

It seems you consider yourself in save haven but still options that this will come back to you is possible.
My number is tax related and not to immigration. Immigration CAN perform background check any time. If they find out still you can have issues. If you in the future want to (re)apply a visa than you will be checked and thanks to my number information is easy to get.

So maybe you will be save on short term but long term nobody knows what will happen.

i understand your situation , and i am sorry that you need money this bad.

all i know is that getting paid under the table is not good , let me give you a quick example...

if you start selling drugs now , will you get caught today? you don't know right ?
whether it will be tomorrow or next year or never , it all comes down to you willing to take the risk.
i would recommend a lawyer who knows about this .
i had a friend who was working in the same company as me but he was a rugby player and the company hooked him up with the job , immigration sent him a letter because he was doing 2 jobs (playing rugby and being a salary man)without permission , it was a huge deal but it got all sorted out and he was able to stay in japan but had to be laid off from the company.

i might be right i might be wrong , one thing that i know for sure is that if i were you i wouldnt get paid under the table.

Good luck sir.

just remember that all the money that goes to your bank account(s) can be tracked by immigration. all of it.

Thank you so much for the concern. I will re-consider my options.
Thank you again for you`ll posts, it was very helpful.