Japanese people think it is important to trust their business counterpart from moral point of view. That's why they think it is impolite to suspect them and they tended to make oral agreement or sign the very simple contract. I would say this is moral-base business.
But in the global business practice, it is standard to sign the thick contract and if their business counterpart will not comply with the contract they would ask penalty or sue their business counterpart. I would say this is legal-base business.
We often see business failures in the global business because there are many Japanese peoples who do not understand these culture gap and mentality differences.
I don't say that Japanese people should cheat their counterpart with bad intention but at least I hope they will not be cheated.
Unfortunately, I don't have actual evidence for above mentioned my thought but I think this way from my experiences. I think that might be the value of experiences.