Even inside Tokyo, that’s very typical for a nice lunch set in an average restaurant.

No it's not. I went there four years ago the average was 1000-2000 yen for the bare minimum at a small shop for below average food. Stop trying to make japan sound like a fantasy world, it isn't.

I’ve lived here for years, not just visited. There are countless restaurants where you get a basic lunch set for ¥500. You’re either going to the wrong places or talking about dinner.

The same places with the ¥500 lunch sets will cost far more at dinner. The cheap lunch is to capture some revenue from the daytime salaryman crowd.

Again, it is not. I don't know why you're fabricating these claims but well I guess it's easy to confuse that with a cheap 7-eleven meal if you've only been there once. Which is probably where you're making up these claims. The reality is that the food quality of these meals are subpar and well for it's price you're paying for what you get. But it's easy to confuse food quality of dishes that are unfamiliar to you so I'll just take it as someone pretending to be an expert rather than maliciousness.

Maybe “nice” is what triggered you? I’m not talking about fancy meals here, just soba, basic fish set, rice bowl, etc. There were like four options within one block of my last office.

And here’s a random list that comes up first on Google; there were plenty of more lists below it:

https://retty.me/theme/100014608/

I live in Japan too. If you drop into a random restaurant it’s most probably going to be around 1000 jpy. You can find food for cheaper but as low as 500 jpy is going to take time to find.