He started athletics in his first year at Misuzugaoka junior high school. In his third year, he qualified for the national competitions. He entered Hosei University, and performed well in the 1500m, 5000m and 10000m sprints in intercollegiate competitions, earning him status as a top track and field athlete at that level.
At the Hakone Ekiden, he placed first in the first leg during his sophomore year, and second place in the second leg during his junior year.
Because of his unique personality, he garnered a lot of media attention and was called “Visual Runner” or “Maverick Running King”. As a top athlete for the Hosei University team in his senior year, Kazuyoshi ran the second leg in pursuit of a new record, but injured his right leg at the 5.4 km point. Although his coach, Michihiko Narita, tried to stop him, he kept running to keep his team in the competition. The spectators were mesmerized as they watched him continue to run, until the coach and team mates finally convinced him to stop. Kazuyoshi became only the eighth runner not to complete the race, and also earned recognition for retiring at the earliest point of the race (28.6 km) in the history of the Hakone Ekiden.
He won the victory in the Japan tournaments in 5000m both in 2003 and 2004. Afterwards, he could not make such good results and had a knee operation. He recovered in 2006 and he was qualified for the Men’s senior 12km at the 2006 World Cross Country Championships of Fukuoka.
He also challenged the first Tokyo Marathon in 2007. He finished at the fifth place. In addition, he entered the Juntendo University Graduate School from April 2007. While being a top athlete, he worked hard for research. In March 2009 he completed his research work.