Pretty good potential I'd say but that star with legs on the left of the last stone, didn't look very Japanese, more like a Christmas decoration.
Then again, the one beside it, looks like 22 boxes/bars with a bomb on top, so hard to say.
Any specific history relating to Jap forces here? Have Japs been trying to enter/buy the property?
Would be safer to speculate ideas knowing more about the history and the situation of the property where these are found on.
Have other TH been exploring here before? Found some sites with multiple markers but only a small handful were original and the rest had all be fabricated by previous visitors to mislead, but these do look faded enough to fit into the timeframe, especially the first 2 pics.
Not financial advice of course.