Junsuke Mizuno

About

Junsuke Mizuno is a Japanese ultrarunner competing in the 40-44 age group whose results across 2023-2025 have established him as one of Japan's stronger athletes at the 100-mile distance on the domestic and international circuits. He holds a UTMB Index of 760 across all distance categories, with his 100-mile Index of 762 reflecting particular depth at the sport's longest standard format. His 2025 season was his strongest yet: he won the Onigajo100 (160km), a demanding race on Japan's Kii Peninsula, in 22:07:20, and backed it up with victories at the MANNO MOUNTAIN MADNESS 87km and the shorter Onigajo Peaks Trail 29km — a sweep across three distances at one of Japan's most respected regional ultra race series. In 2023 he won the Chianti Ultra Trail 103km in Italy, an international result that placed him among the world's best at that distance. His 32 UTMB Index races and consistent podium performances across multiple formats reflect a methodical approach to competition across the full distance spectrum.

Notable Wins

• — Onigajo100 160K 2025 (22:07:20)
• — MANNO MOUNTAIN MADNESS 87K 2025
• — Chianti Ultra Trail 103K 2023

Race History