"Tycoon" is interesting, because it's not really a Japanese
term. The Japanese word was ôkimi
. What happened was that the Chinese on-reading
was used to interpret the characters, rather than the native kun-reading
that the Westerners didn't know yet.
Even ôkimi was a crappy way to refer to the shogun. It was actually nothing more than a title conferred by the Emperor. In the pre-samurai days of Japan, ôkimi were the people running the temporal world, and by the time white folks started showing up, the entire system had changed to make the title effectively moot.
Anyway, if you use the word "tycoon" with a Japanese person, it will probably confuse them. They might think you're saying taikû, which means "anti-aircraft."