Japan's the fourth largest economy in the world and, given how cheap rice is, it being 1x, 5x or even 10x average I'm sure is insignificant to 95%+ of people.
For perspective, it's about 2x what you'd pay in a UK supermarket. What's the big deal?
Its been progressively becoming more expensive for the last 18 months. And Japanese wages are the same as the 90's and they have millions of pensioners that can't absorb a higher price.
"rice" and "meal" are synonyms in Japanese language. Food in day-to-day Japanese cooking mostly consider what and how to pair with rice off the cooker. And "the food" is suddenly costing double. It is a big deal.