In a word: no. Japan has a different attitude toward civil rights than the west. Can anyone point to source from within Japan?

No. There are serious and so far unfounded allegations of coercion of suspects and witnesses in this thread. That's not what I meant by "a different attitude toward civil rights".

It almost seems that you're trying to have it both ways. Routinely conducting three weeks (or whatever period) of ceaseless interrogation is as bad for civil rights as it is for actually finding the truth in an investigation. Either tell us that such practices are fine because cultural differences, or tell us convincingly that they don't actually happen. Pick one.