A question about “part time work” legitimacy

A question about "part time work"
So, I was recently offered this very small, cozy little casual gig. A youtube personality in the US offered me $5USD for each yt short/instagram reel I can edit and slopify for him, lol. Seems pretty nice, yeah? However, I dont need to contact immigration and get some "permission to engage in other activies" addendum put on my visa do I? It would just be a very casual cash flow, probably through PayPal, not formally contracted. (I know this youtuber through a connection of mine, so hes "good for it") Can I just stress-free do this editing work and accumulate a nice little pile of cash in my American bank account while in Japan or am I going to get myself deported? I assume a lot of you guys in Japan make some kind of side revenue through social media or other online means, and wondered if I was overthinking this. Im trying to be smart here. Much appreciated!

by 501stGeneral