Engineer/Specialist in Humanities/Intl Services visa and Freelance Side Work

Just looking for a little advice or reassurance about a potential visa misstep.

I'm in Japan on a Humanities/Engineer visa, working full-time teaching. To help with family costs back home, I did a photography job for a Japanese company (they sought me out for my 'international eye'). I've already invoiced the client but haven't been paid yet. It's work I'm very familiar with, as I was a professional photographer in my home country for years, and I've been hoping to eventually do it here too. My main company assured me from the get-go when I was hired that they don't mind if I do photography as well.

After the fact, I realized my visa doesn't automatically cover freelance photography (yes, I was very silly reading blog posts online about how "wide" the scope of this visa is). I've since learned I need "Permission to Engage in Other Activities," which isn't retroactive. And as there's no steady freelance work with working hours or one main client/employer, I'd have to leave that section of the document blank. I've already invoiced the client but haven't been paid yet.

Now, I fully intend to report this income and pay taxes on it. I consulted an immigration lawyer and they suggested applying for the permission and highlighting my professional history as a photographer and the need for extra income. I'll be reporting this income (likely as misc. income as it was less than ¥100k)

My main fear is the consequences (one might say too late, but I was just so happy to finally do something in my preferred field). My visa renewal isn't until 2027, but I'm pretty anxious about getting hemmed up. For this issue that I'm trying to be fully transparent about, what are the realistic chances of this leading to serious trouble like deportation or a non-renewal (or worse)?

Has anyone been in a similar situation with a one-time gig (or have links to good immigration lawyers, I've been making a list)? Any insight would be a huge help for peace of mind. I've also kind of made peace with the fact that I screwed up and might need to get my finances in order to undergo potential deportation (some might say I'm pessimistic, I'm just trying to be realistic).

TL;DR: Did a freelance photography job in Japan while on a Humanities visa. Realized too late I needed separate permission from immigration. My main employer is supportive, and I plan to report the income and pay taxes. For this mistake, how likely is serious punishment?

by Alternative_Face_602