[From Tsuzuku Jinsei o...]:

As the pioneer Evangel, it is Lufiras' job to rid the world of lower level demons who cause mischief. No hero can go without a sidekick, so Cadiz the (slightly annoying) Intermediate Level Demon decided to descend to earth as well to make sure his little buddy Lufiras-chin wouldn't go lonely. Together with Manaka, who (reluctantly) allowed them to freeload off her during their stay in Japan, they go on their way exterminating low level demons, eating kakigoori (shaved ice thingies) and causing a racket at school.