Or rather, he fights J. Carroll Naish pretending to be a Japanese prince/scientist named Dr. Tito Daka (even though "Tito" is not a phonetically possible Japanese name) and speaking with something closer to a Brooklyn accent than anything remotely Japanese. (Although I think Naish might have been trying for a Chinese accent, because it sounds a bit like the accent Benedict Wong uses for Wong in the MCU. Americans have historically tended to conflate Chinese and Japanese, even though the languages aren't even in the same family.)
Like a lot of superhero/adventure fiction during WWII, it's set stateside and focuses on the fight against foreign saboteurs and infiltrators. It's also racist as hell, opening with narration praising the "wise" US government's decision to force Japanese-Americans into concentration camps.
It's mainly notable for introducing the Batcave and the familiar appearance of Alfred. The comics sent the original chubby, Oliver Hardy-esque version of Alfred to a health spa and slimmed him down to make him look like the actor from the serial.