I've been working on implementing this game in Ai Ai, and have realised that there is an error in the write-up here: the Knight does not promote to Gold General in Tengu Dai Shogi, it promotes to a new piece which moves as a Chess Knight or as a Gold General. The text description and diagram are visible under the 桂馬：けいま heading on the original Japanese page.
I've been working on implementing this game in Ai Ai, and have realised that there is an error in the write-up here: the Knight does not promote to Gold General in Tengu Dai Shogi, it promotes to a new piece which moves as a Chess Knight or as a Gold General. The text description and diagram are visible under the 桂馬：けいま heading on the original Japanese page.