The claim that Japan is "safe" because it has a high conviction rate is a junk meme. The United States federal conviction rate is essentially identical to the Japanese judicial conviction rate when measured by the same methodology. It's roughly 99.6-99.8% depending on the year.

Japan is safe because of other factors, not their conviction rate.

> they swipe up every single criminal they can, plus a bunch of random people

And this is completely baseless.