Most of the quail live a couple of years, from what I hear. This is my first year with them, though... I'm sure their care has something to do with it, too.
I think you're the first person I've seen from Japan!!
I raise them for meat, eggs, pets, all of the above. But I can't keep enough of them around to try the meat. I sell the eggs, but if I have a surpluss I boil them and feed them back to the birds as a treat.