His best singles results were reaching 10 Challenger finals – Bangkok, March 1998 (l./ Leander Paes); Kyoto, March 1999 (l./ Julian Knowle); Córdoba, July 1999 (l./ Oleg Ogorodov); Madrid, August, 1999 (l./ Ota Fukárek); Hong Kong, October 1999 (l./ Stéphane Huet); Hamilton, New Zealand, March 2000 (l./ Michael Joyce); Seoul, October 2001 (l./ Hyung-Taik Lee); Yokohama, October, 2001 (l./ Takao Suzuki); Campos do Jordao, July, 2003 (l./ Giovanni Lapentti); and Burnie, February, 2005 (l./ Chris Guccione).

In ATP Tour events, Motomura's career match win-lose record in singles was 9 and 25, and he never advanced beyond the second round of a tournament.

In doubles, he played in one Grand Slam, the 1999 Wimbledon Championships partnering Adriano Ferreira.

Late in his career he and partner Satoshi Iwabuchi compiled a 14 and 2 win–loss record in four Futures events.

Motomura's biggest match wins were over Tim Henman in 1994; a young Tommy Haas in 1996; Paradorn Srichaphan three times, in 1999, 2001 and 2002; World No.

He won the doubles title three times; in 1993 and 1995 partnering Tetsuya Sato; and in 1996 with Thomas Shimada.