The Collaborative International Dictionary of English v.0.48:

Nipponese \Nipponese\ n. [From Japanese nippon, Japan.]
   a native or inhabitant of Japan.

   Syn: Japanese.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Nipponese \Nipponese\ adj.
   Of or relating to or characteristic of Japan or its people or
   their culture or language; Japanese.
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

Nipponese
    adj 1: of or relating to or characteristic of Japan or its
           people or their culture or language; "the Japanese
           Emperor"; "Japanese cars" [syn: Japanese, Nipponese]
    n 1: a native or inhabitant of Japan [syn: Japanese,
         Nipponese]