- Born:24 February 1999 (21 years)
Japanese judoka Koshi Nagai took the bronze medal at the World Junior Championships in Zagreb in 2017. He won the World Junior Mixed Team Championships in Zagreb in 2017. He captured the gold medal at the Junior European Cup in Berlin in 2019.
Competitions - Medal overview B S G
- World Championships Juniors 100
- Continental Championships Juniors 001
- European Cup Juniors 001
- European Cup Cadets 001
- National Championships Juniors 010