I didn't expect I'd be a target. I didn't keep the key in the house because it would be bothersome.

My neighbor never lock their front door...

I never lock my front door, either. But those who steal from farmers deserve eternal perdition.

There's been a continuing rash of this throughout rural Japan.

So if this hasn't happened (very much) before, then why is it happening now? And no, it's not because food is more expensive now in Japan (you should have seen the supermarket prices in the 80s!!.)

Criminals are not generally very bright, they are parasites who pick on the weak and go for easy pickings, once they realise there is an opportunity in rural areas (cases reported) more of them will look to profit from lax security. Unfortunately once they start it will go on and farmers are going to have to take much greater care with their security or they will continue to be targeted. It’s happened in other countries, Japanese farmers have been lucky until now if this is only now beginning to be a problem.

Perhaps public flogging for such criminals might be an effective deterrent; publicly humiliated?

Before blaming this on foreigners, I'd like to see proof. I know, it's an old concept.

Wonder where those foreigners online sellers and door to door sellers get their cheap rice and other food items. Yrs ago there was a news item about an old Japanese man who steal vegetable products form some farms and sell it very cheap just for the thrill of being around young and beautiful housewives. So yes, not blaming all foreigners though.