Nipponese vs Asian

Nipponese and Asian both are nouns.

Word	Noun	Adjective	Verb	Adverb
Nipponese	Yes	Yes	No	No
Asian	Yes	Yes	No	No

As nouns, Asian is a hypernym of Nipponese; that is, Asian is a word with a broader meaning than Nipponese:

Other hypernyms of Nipponese include Asiatic.

Nipponese (noun)	Asian (noun)
a native or inhabitant of Japan	a native or inhabitant of Asia

Nipponese (adjective)	Asian (adjective)
of or relating to or characteristic of Japan or its people or their culture or language	of or relating to or characteristic of Asia or the peoples of Asia or their languages or culture