Joining different company from COE

So I am waiting for my COE right now sponsored by the new company in Japan, but the job isn't the best and there were some discrepancies in the employment agreement and what was discussed (unfortunately I had signed it anyway). Now I have found another company in Japan who wants to hire me and thats great but my dilemma is that its been more than 2 months already since we applied for the COE from the first company. I have already pretty much packed up everything here and sold most of my stuff, so I dont want to wait another 2-3 months for the COE from the new company.

My question is:
Is it possible to go to Japan using the first company's COE and Visa, and then join the second company directly. Is this illegal in anyway or just unethical?

when you cancel your contract before you come to Japan, the company need to inform this fact to immigration. the COE may be canceled at this time. (even if you have a visa on your passport, if immigration cancel the registration, you may be refused at immigration control in airport.)
on the other hand, when you don't cancel the contract, you may be able to enter Japan although you have no intension to work in that company.
the argument point is that, from the standing point of immigration office, it is hard to know your true will.

the answer is, if you ask immigration the question exactly in the same way as you do in this forum, they will surely say "No, you can't.", because you clearly tell that you don't want to work in that company. (their answer of the denial may be generous, because it could be a fraud application of COE and a fraud usage of COE. it could be crimes.)
but, if you question it in anther way, they may not say "No".