So I stumbled upon this place after seeing a green beam of light appear at the top of a mountain near Mogg Latan's shrine: if you go into this green beam of light, a green fog surrounds you and you see those green glowing ghost-like animals at a pond near a cherry blossom. The animals and the green light disappear after a while. So far, it seems to happen randomly in the afternoon.
What are those things? What's their story? What are they called? Has anyone in the game ever given any info on them? Only thing I found is someone (or something) mentioning hitting a rabbit with an arrow to get treasure, the same kind of rabbit that is also seen in that place (but it can also appear in other places).