Ground: Hardcourt outdoor
| ITF M15 Hinode | 2025/03/12 01:00 | Yuta Kawahashi v Hiromasa Koyama | 6-2,6-3 |
| ITF M25 Sapporo | 2024/09/08 01:00 | Kohei Hayashi v Hiromasa Koyama | 6-2,6-4 |
| ITF M25 Sapporo | 2024/09/05 03:10 | Hiromasa Koyama v Keisuke Saitoh | 0-6,6-4,3-6 |
| ITF M25 Sapporo | 2024/09/03 03:00 | Hyeon Chung v Hiromasa Koyama | 5-7,1-6 |
| ITF M15 Tokyo | 2024/07/10 06:15 | Kenta Miyoshi v Hiromasa Koyama | 6-1,6-2 |
| ITF M15 Tokyo | 2024/07/03 03:30 | Hiromasa Koyama v Ryotaro Matsumura | 4-6,5-7 |
| ITF M15 Hinode | 2024/03/11 01:00 | Hiromasa Koyama v Hong Kit Wong | 7-6,3-6,4-10 |
| UTR Pro Noda | 2023/08/26 00:00 | Hiromasa Koyama v Paul Howe | 6-7,6-7 |
| ITF M15 Hinode | 2025/03/16 05:00 | Tai Leonard Sach v Hikaru Shiraishi | 2-6,2-6 |
| ITF M15 Hinode | 2025/03/15 02:00 | Ryo Tabata v Tai Leonard Sach | 1-6,6-7 |
| ITF M15 Hinode | 2025/03/14 01:00 | Tai Leonard Sach v Ji Sung Nam | 3-6,6-2,7-5 |
| ITF M15 Hinode | 2025/03/13 02:30 | Tai Leonard Sach v Daiki Yoshimura | 6-0,3-6,6-1 |
| ITF M15 Hinode | 2025/03/11 02:30 | Sanhui Shin v Tai Leonard Sach | 2-6,4-6 |
| ITF M25 Burnie | 2025/02/18 01:00 | Tai Leonard Sach v Scott Jones | 6-7,2-6 |
| ITF M25 Timaru | 2025/02/10 21:00 | Shinji Hazawa v Tai Leonard Sach | 7-6,2-6,6-4 |
| ITF M25 Timaru | 2025/02/09 23:07 | Tai Leonard Sach v Ryo Minakata | 7-5,6-4 |