For most people, the critique of Japan is because their own countries used to operate jails in this way.

So rationalizations of why it’s appropriate because the person was suspected of XYZ isn’t going to land with them and is largely irrelevant.

But I don’t mind playing devils advocate.

Should the justice system force confessions out of murderers? No, because they are only potential murderers and we have historically been able to get innocent parties to confess. People with vulnerability such as mental health problems are even more likely to give false confessions. The goal of requesting testimony should be honesty not compliance.

This logic applies as well the drug dealer, drug users, and jay walkers. It’s a moral principle disconnected from any specific geography so even if we are not Japanese and have no intention to interact with Japan, we can say they have not lived up to that principle.