Level, 1 wins each over 2 singles meetings since 2025. Last meeting on 29/05/2026 at M15 Karuizawa.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 29/05/2026 | M15 Karuizawa | Quarter-final | clay | Koyama | 6-7(0) 6-2 3-6 |
| 03/07/2025 | M15 Tokyo | Round 2 | hard | Shiraishi | 2-6 0-6 |
| clay | Shiraishi 0 - 1 Koyama |
| hard | Shiraishi 1 - 0 Koyama |
| 2026 | Shiraishi 0 - 1 Koyama |
| 2025 | Shiraishi 1 - 0 Koyama |
174 wins, 94 losses since 2021 (64.9%).
Last matches: D D V V D
38 wins, 39 losses since 2021 (49.4%).
Last matches: V V V V V
Level, 1 wins each over 2 singles meetings since 2025.
On 29/05/2026, at M15 Karuizawa (Quarter-final): Hiromasa Koyama won 6-7(0) 6-2 3-6.