Opening and Ending songs, the soundtrack heard is an inspired approach to the modern dwellings of "Hellsalem" that which once was "New York City", in the fictional world of "Kekkai Sensen" AKA "Blood Blockade Battlefront" anime!
A preview of five tracks from the OST - with music composed by Iwasaki Taisei - has hit the net, and previewed here. The soundscape features a rich fusion of big band, swing, jazz ("Catch Me If You Can, Snap Out", "Footloose") - which truly fills the anime with a certain depth somewhat associated with the grandeur and glamour of old time big tunes, IMHO. There's also a tinge of "fun pop" with "Toy Blues", and of course the pre-requisite "heavy" opening theme. Have a listen.
UPDATED: All tracks since uploaded on youtube. The OST can now be purchased now on Amazon!
The album also features the TV size version of “Hello, World!”, the opening theme by Bump of Chicken. The song caught on after it was released with a promotional video before the broadcast began. There is no doubt that this will be an indispensable item for fans. Further details including the song list will be announced on the official site once they are determined. The soundtrack will be released on July 15 and cost 3,300 yen (plus tax)." - reported Otaku Mode.