Japanese capital vs Nippon

Japanese capital and Nippon both are nouns.

Word	Noun	Adjective	Verb	Adverb
Japanese capital	Yes	No	No	No
Nippon	Yes	No	No	No

Japanese capital (noun)	Nippon (noun)
the capital and largest city of Japan; the economic and cultural center of Japan	a constitutional monarchy occupying the Japanese Archipelago; a world leader in electronics and automobile manufacture and ship building