Complex sentence: Arriving at the surface the trio discover the apocalypse which had befallen the world and take refuge in Roppongi before they are attacked by, which Hibiki manages to easily defeat with his demon Byakko.
Split into simpler sentences: Arriving at the surface the trio discover the apocalypse which had befallen the world and take refuge in Roppongi. However when they are attacked by a creature called, Hibiki manages to easily it defeat with his demon Byakko.