The Tenma Bridge is a sturdy construct that supports JAPAN and serves as its only connection to The Continent. Since JAPAN is not supported by any of the Holy Beasts, the Tenma Bridge is also the only thing keeping JAPAN from crashing to whatever lies below The Continent.
On the continental side it connects to Portugal of the Free Cities Alliance, and on the JAPAN side it goes to Morocco. Both Portugal and Morocco have developed into great economic powers due to trade between the Continent and JAPAN.
During the events of Sengoku Rance, the Demon Lord Xavier planned to destroy JAPAN and kill everyone living in the country by tearing apart the Tenma Bridge. His efforts involved the Youkai Ishijijii, who can grow endlessly, to overburden and crush the Bridge. Ultimately he is stopped by Rance.
- For real world reference, see 天満橋.