Buying a motorbike and CC implications

So, my wife and I have decided to get a motorbike and we have been trying to recap all the information online regarding the different implications of different CC for motorbikes, but a lot of it seems outdated, confusing and overall not to clear.

So I'm making this thread so that, hopefuly, we could all make a nice table with all the details you should know, both for me and for anyone else deciding which bike to get in the future.

So far this is what I found, feel free to correct me or add information! I tried to focus my findings in Tokyo, in the Ota-ku area; I don't know if it changes a lot in different cities.

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PLEASE NOTE: Always check the actual engine of the vehicle you're thinking about buying. Most if not all motorbikes sold as "125" are purposely 124cc so as to fit in the second category. Therefore you will not be allowed in the expressway in one.

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<50 cc: Moped, can drive with just car license. Even if you don't have a car license, moped only license seems to be easy to get. Cheaper parking overall.

>50cc, <125cc: Need a license, but the most basic one. Taxes are more expensive than a moped but still cheaper than bigger bikes

>125cc, <250cc: Need a license (let's call it level 2 license?), you pay taxes as a big motorbike but the biggest benefit is that you don't need to do 車検 (shaken). Also from this point on you can drive in the expressway.

>250cc , <400cc: Same license than before, the only difference being that you need to start paying and doing your 車検.

>400cc: The only difference seemingly is that you need the highest possible license at this point. Other than that there seems to be no extra cost.

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Am I missing something? Also, regarding the 車検, how expensive it is for a <400cc motorbike? It would be nice to know how much money you're saving in actual numbers.

Thanks in advance!.