N. Koizumi defeated Yuta Kawahashi 7-5 6-3 in the M15 Tokyo 1 round of 32 on hard. N. Koizumi extended 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 |
| 2025-06-05 | M15 Karuizawa 1 | R16 | clay | Yuta Kawahashi | 6-3 6-0 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.