They're all localized in the Yamanote Circle - which is a part of Tokyo that's surrounded by a railway line. There was a barrier put up by the military, who were told to do so by the government which has had warnings from angels. Which yes, exist in my world, though most people didn't know that they or demons were real until very recently.

The Lockdown is over now, though the resolution is... less than ideal. The whole thing was part of the War of Bel, the war for the title of King of Demons, and the sole human that could win did win... but chose to turn his power over to God. Now, if humanity so much as makes one wrong move, God will take their free will away.