Have a Japanese character, name him the Rising Sun or somesuch. Emphasize his samurai roots, making it all honourable and all lonely-warrior and ignoring the sordid history of the samurai, have the character be typically Western-portrayed Japanese hero (stoic, quiet, probably small, but capable of immense violence without even blinking).
What makes this character ANY different from any other Japanese hero in a superhero comic?
The Union Jack story was stereotype upon stereotype that had a B-movie ethos strung throughout.