Source: Wikipedia Tenra War
available under the CC-BY-SA License.
The setting is based after the intercontinental war between two continents: Tenra (similar to a high-magic Japan in the Sengoku period) and Terra (similar to a United States in the Wild West). After the war, the world was changed by the influence of great culture clash between oriental and occidental nations. The game starts from that point, after the two cultures have had some time to intermingle. That's when the mysterious alien "Angels" arrive, great psychic/magical creatures with strange and unknowable motives. The basic setup of the game is two radical cultures joining together to fight off an alien invasion.
There are over 40 character classes based on oriental and western cultures in basic rulebook, which include houshi (buddhist monk), Jinguuke (Shinto's agent belonging to the Jinguuke clan), ninja, onmyouji, samurai, Yoroi-nori (mecha pilot), gunslinger, preacher and private eye, rocket ranger (member of US Army's special airborne forces) , saloon girl and steam mage. To emphasize the cultural mashup, classes are mixable: One could create a ninja gunfighter, a Taoist Sorcerer Catholic priest, a kugutsu (living doll) saloon girl, and so on. Oriental and western characters fight against the angels that are arch-foes of humankind together.