Not really the same thing. They're much larger already than most stores you'd see in urban Japan.

Think more in terms of small convenience stores ("Spätis" with daily necessities) everywhere. Typical distance to a store is maybe 500-1000m in Germany. In dense areas of Japanese cities it's closer to one store every 100m-200m.

So in Germany it'd be a 10 minute walk, while in Japan most of your "walk" would be getting downstairs.

The flipside of that is that selection is going to be limited compared to what you'd find in Germany.

I see. What you describe does seem to match what I experienced in NYC, Portugal, and Spain? Small supermarkets everywhere with a bit of a random selection of items