He made his international debut on grass at the 1999 IAAF World Cross Country Championships, but was outside of the top 100 of the men's short race. He was runner-up at the Japanese Championships that year, but returned to the fore in 2000 with wins at both the national championships and games. The emergence of Yoshitaka Iwamizu at the 2001 Japanese Championships marked a generational change. Although Uchitomi ran a time of 8:29.63 minutes (third best in his career), he was beaten by Iwamizu, who would go on to win five consecutive titles. Uchitomi defended his title at the 2001 East Asian Games and improved his own games record to 8:33.98 minutes, beating compatriot Wataru Izumi into second place as he had in 1997. He also took the steeplechase title for the Chugoku Electric Power Company at the All-Japan Corporate Track and Field Championships.