It's pretty delusional even in Japan, nobody seriously expects Russia to return them. Early in the post-Soviet era there were some serious-ish proposals about Russia handing them back in exchange for massive financial aid, but ever since Putin took the reins it's been obvious that this is just not going to happen.

I don't think even the Japanese government wants them back at this point, Hokkaido (the nearest big island) is already rapidly depopulating and having to administer a bunch of semi-frozen islands with random Russian pensioners and no resources aside from fish would be a logistical nightmare and permanent drain on the treasury.