mythusmage
Prince
Looks like you don't have the Japanese units that were included with Civ3: Play the World but not Civ3:Complete. Firaxis released them as a download on this site but I can't seem to find it. Anyone?
A bit late I realize, but my copy (Mac) of C3C has the Sengoku scenario in ...Conquests Game Data\Conquests\Sengoku... in the ...Art/Units... directory. That might be where the required files are in the PC version.