Looks like everyone is setting up a a complicated game of "who can you trust?", with even Krona getting in on the act.
Of course the kids can sight-read Morse code.
IF the name of the band that does the opening credits music, Uverworld, sounds familiar, it's because they've done the same for about a zillion anime shows, live action anime movies, and video games, starting with Bleach in 2005.