Was the father of graffiti Japanese?
Arguable, but it's pretty much accepted that modern urban graffiti art started with the graffiti artist Taki 183. Despite a Japanese sounding name, Taki was in fact a Greek-American youth in the late 1960's who tagged his name all over the NYC landscape, setting in motion the underground culture which has snowballed to a global level.
Near my Japan residence, the Tamagawa Bridge has it's fair share of graffiti art. It's doubtful my neighbors have the same fascination as I do since I can remember graffiti in it's early days in 1970's New York.
Graffiti in Japan is just as expressive, urban, rebellious and rhythmic as anything on the NYC subway trains before technology destroyed subway art culture literally overnight by the late 1980's. Despite that, graffiti art has survived and grown exponentially since then.
There are tag names, graffiti characters to be sure, but the use of Japanese kanji, katakana or hiragana is notably absent. At least I haven't seen it. It seems Japan's graffiti artists prefer western words or sounding names to Japanese ones. However the picture below seems to be a combination of stylized kanji and hiragana.