Working in second job

Hello all
I have started working in Japan last year after graduating from university.
I currently work from home on 技術・人文知識・国際業務 visa working on IT job as seishain Full time.

I am thinking of doing freelance/part time IT job for another company as well while working in this company.

I never took any action, thinking it would be illegal. But now that prices are going up and I have too much free time on my hands, I am now seriously thinking about it.

My question is, can I just start working in another company? Part time or as a freelancer? Get paid in the same bank account as my main job. without notifying anyone (immigration etc.)

My current company allows for second jobs. I am just worried about immigration and other things.

by exivor01