Originally a shot putter, Koshi's first attempt at sliding sports fell short when he failed to make the Japanese bobsleigh team for the 1992 Winter Olympics in Albertville, France.
[1] Koshi also competed in the FIBT World Championships, earning his best finish of fourth in the men's skeleton event at Nagano in 2003.
[2] After skeleton was added to the Olympic roster in 2002 in Salt Lake City, Utah for the first time in 54 years, Koshi qualified and placed eighth.
Continuing to compete internationally at an age when many Olympic athletes retire from competition, Koshi gained a measure of fame at home, and was referred to in the media as, "the hope of the middle-aged.
"[1] Koshi qualified for his third Olympics, the 2010 Games in Vancouver, British Columbia, Canada, and competed in the men's skeleton event there, but finished in 20th place.