While I am unfamiliar with Japanese patent law, this would certainly be sound under the American system. Two requirements for patentability are novelty and non-obviousness, meaning the idea does not already exist nor is it such a trivial modification of an existing idea that anyone knowledgeable in the subject could come up with it. Anything an AI spits out is pretty much by definition something that either exists in their training set or which can be trivially deduced from something in their training set. They might be a useful tool for an inventor, but the creative spark which patents protect can not come from them.
> Anything an AI spits out is pretty much by definition something that either exists in their training set or which can be trivially deduced from something in their training set
What? Have you used modern frontier models? I find it very hard to believe you could interact with them much and maintain this level of misapprehension.
Provide specific examples of AI providing something novel. Eliding something from a vast dataset that would take humans longer to analyze is helpful, but not novel.