Japan has the Whistle-blower Protection Act ("WPA" )which essentially categorizes three types of whistle-blowing.
One type is internal whistle-blowing like the boss or the ethics hotline. In such a case, whistle-blowers are strongly protected. Only as long as the whistle-blower considers the illegal facts occurred or were about to occur, whistle-blowing is protected. Article 3(i).
Another type is whistle-blowing to administrative authority. In this type, intermediate protection is given. When there are reasonable grounds to believe that illegal facts occurred or were about to occur, whistle-blowing is protected. Article 3(ii).
The other type is whistle-blowing to mass media or other organizations neither internal nor administrative authority. In this case, at least, there should be reasonable grounds to believe that illegal facts occurred or were about to occur, but that is not enough. Additionally required are reasonable grounds to believe either (1) other types of whistle-blowing would cause lay offs or other disadvantageous treatment, (2) internal whistle-blowing would cause concealing the evidence, or (3) the boss asked the whistle-blower not to resort to whistle-blowing. Article 3(iii).
The "protection" means the prohibition of firing or any other disfavorable treatment because of the whistle-blowing. Article 3 to 5.
One good thing is that the WPA covers the protection of government officials. Article 7. Also, the Q&A by the government on the WPA stipulates that as the protected whistle-blowing is on illegal acts, it is considered not worthy of protecting as secret, therefore whistle-blowing would not violate the obligation of confidentiality. This means that if the requirements of the WPA are met, Japanese Manning may receive protection.
But there are some uncertainties. One of them is how the court would interpret the statute. In one well known classic case, the Japanese Supreme Court upheld the conviction of a journalist of a newspaper for soliciting to disclose classified information. People v. Nishiyama, 32-3 Minshu 457 (May 31, 1975). Although the way he seduced a female government official is questionable from the journalists' ethics (he approached the official and formed a sexual relationship for obtaining classified information), this case would suggest that depending on the circumstances, the court may interpret the language of the WPA very strictly.