To my eyes: you send a formal letter to Apple, describing the issue, with proof of purchasing and advise them if they do not unlock your device, regularly purchase they have to respond to a formal aggravated theft complaint because not only the device it's yours but also you data (a copy of them, maybe) it's on it and their tool prevent you to access them.

I do not know the Japanese law but here in EU such complaint PLUS a copy with some chatty journals will make the deal VERY quickly.

Sometimes peoples tend to avoid biting when they should.