Kuki, a right-hander, played collegiate tennis in the United States for UCLA.

[2] His best performance in a Grand Slam tournament came at the 1971 French Open when he had wins over Phil Dent and Petre Mărmureanu, before losing a five-set third round match to Bob Lutz.

[3] In April 1976 he had the most prolific period of his career when he finished runner-up in a further two Grand Prix tournaments, both in Spain.

He lost to Paolo Bertolucci in the final at Barcelona, then to Buster Mottram in Palma, Majorca.

[4][5] A regular Davis Cup competitor for Japan in the 1970s, Kuki played the last of his nine ties for the Japanese team in 1978.