High taxes on older cars in Japan?

I have heard that most people in Japan do not keep their cars for a long time but trade them in after a few years. I'm told this is because there are high taxes on high mileage older vehicles so people there prefer to buy another card rather than pay the higher taxes, is this true?

I have no knowledge about tax but I believe people change cars frequently to save "Inspection Cost," which generally costs 100,000-150,000 yen.

Yes,high inspection cost and high emission fee becos older cars don't have emission control system such as catalytic converter.

What you are referring to is, as JLady mentioned, most likely the "shaken" or inspection fees that occur every 2 years. The more repairs needed for the car to pass inspection (which increase with the age of the car) the more expensive it will be. Eventually the cost of the inspection can exceed the value of the car and there is a point where used vehicles are only worth the amount of its inspection fees. It gives increasing incentive to look for a new (or newer used) car whenever the shaken time comes around as you may end up saving money.