I've attached one of the images as the other images haven't really shown anything I would possibly view as a character form. The Japanese language does use Chinese characters in its writing. I've put a circle and an oval around two areas That could be characters. But I'm guessing it's more pareidolia than anything else. The oval circle looks like deep carved 大 which means big but it's branching off to a couple of lines/strokes which looks unusual. The circle is in a bright washed/corroded out area of the photo that looks like a shallow surface character carve. Like the character 東 which means east but I'm only 5% sure for both circles. Like I said before it's more of a case of pareidolia. Good luck.