Yuta Kawahashi defeated N. Koizumi 6-3 6-0 in the M15 Karuizawa 1 round of 16 on clay. Yuta Kawahashi claimed a first win over N. Koizumi in three meetings, narrowing the head-to-head to 2–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2026-07-07 | M15 Wuning 5 | R32 | hard | N. Koizumi | 6-5 |
| 2025-07-02 | M15 Tokyo 1 | R32 | hard | N. Koizumi | 7-5 6-3 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.