Ka kammala wannan magana: A ranar 13 ga Agusta, 1971, sa'ad da Nagai yake ɗan shekara 19, ya buga wa Japan wasa na farko a wasan da suka yi da Iceland. Ya kuma taka leda a wasannin Olympics na 1972 a shekarar 1971. Kodayake, bai buga wa Japan wasa ba a 1972, an zaɓe shi Japan don cancantar gasar cin kofin duniya ta 1974 a 1973. Ya kuma taka leda a
Wasannin Asiya na 1974, 1978. A shekarar 1980, an zaba shi Japan don cancantar wasannin Olympics na bazara na 1980, rashin nasarar Japan don cancantar wasannin Olympics na bazara na 1980. Wannan cancantar ita ce wasan sa na karshe ga Japan. Ya buga wasanni 69 kuma ya ci kwallaye 9 don Japan har zuwa 1980.