Nihai Tower

Nihai Tower is the great watchtower that stands on the only road to Yogo Shiro, guarding a treacherous bit of swamp and cliff walls. From it's vantage point on the edge of Seikitsu sano Yama no Oi it's guards can see watchfires in borth Yogo Shiro and Shiro no Shosuro. Messages can be passed between the two castles in this manner, and no one outside the Scorpion have ever managed to decipher the code used. (3E p. 297)