This is pretty appalling. I don't think the burden is on the offerer to explain the contract in full to you. I feel bad for you, but you kind of shot yourself in the foot on that one.
This last person went through the entire contract and explained in layman's terms what each section meant. Considering I'm close to illiterate in Japanese (though I could decipher enough to realise the part that says "you can leave so long as you give 1 month's notice"), I pretty much trusted the guy on what he was saying, but I imagine it's a nice service to have.
Considering that startups are often talked about like a sort of second family sense, the fact that some sort of deception happened on the employment contract is good cause to not want to ever associate with such a startup.
If the founders knowingly presented a contract that he couldn't possibly understand without an explanation, then this seems to be an abuse of trust, plain and simple.
People keep thinking this situation should be about contracts and lawyers and staying silent to help his case in a lawsuit or something. The employee know full well that he is never going to get fully paid for the contract. So he decided to let other people know how bad this company is so others can know about it. This is the best way to punish a company that acts in bad faith.
To be fair, the employee should have asked for a translated contract upon being presented with one in a language that he doesn't understand.
Foolish or badly advised people still have rights you know
If they were offended, that would be even more of a reason not to work there or sign it.