I renewed last year (here). The 'obstacle' (increased scrutiny) was a refresher course to be taken at a local driving school. It took a good couple hours--kind of typical classroom talk, but then some rather thorough eye testing. Not only ID where the gap in the circle is, but peripheral vision and so on. Then also a driving test, but this was not a 'real'/strict test, but I think just enough to see if you could handle a car fairly well. Do a couple laps, stop and go, traffic signals, lane changing to go around a stopped car, and one stretch where the key was to get up to 40-50m/hr and hold it, I guess to see if you could handle some typical city speeds without blocking traffic. IIRC, this cost ~¥6000.
On reserving my time slot for this, I was told it was not a pass/fail thing, but anyone who failed would not get the certificate of completion, which was what you then took to the license center. And with that in hand, the processing at the license center was easy. A quickie eye test, picture, skip the usual lecture, and wait a bit as a group of elders for them to bring out the finished licenses, and call names to pass them out.
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My dad, now gone, had a valid license when he passed away at 97. He was able to opt for a license/testing center that was easy, kind of the next town over from where he lived. He had 'Ex POW' plates on his car, and my sibs speculated that he had found some examiners that simply passed him for that.