Basically describe your invention vaguely. Government officials will see the details and decide award it. Nothing detail is published. This is not USA where freedom of information act doesn't apply. Enforcement of patents usually lies in the person or entities holding the patents. So if governments chose not to enforce the "publication" parts, that means it is up to patent holders to do so. For example Tesla open up their patents. Here Japan probably wants to protect their own companies from devalue their own IP and RnD helping copycats achieve similar result without the expenaive research part. Patent is just staking a limited period exclusivity with a requirement to describe publicly exactly how you do it. Remove that "publicly" and "exactly" won't negate the idea of patent. Enforcement might get some difficulties though.