I would like to see the Japanese Parliament debate declaring war on North Korea. I would wager that no one in North or South Korea and especially not China wants Japanese Army boots on the ground in that part of the world. Too many horrible memories of what happened the last time Japan’s military invaded mainland Asia.
PM Abe (who was returned to power with a reduced mandate) has just managed to convince his coalition to at least consider a Constitutional change allowing Japan to participate in regional defense activities beyond their borders. A war declaration without an attack is simply not within the realm of possibility despite what many warhawks here seem to want.