| ITF Japan F4 | 2017/03/25 02:00 | Hiromasa Oku v Masaki Osafune | 1-6,0-6 |
| ITF Japan F3 | 2017/03/18 03:00 | Yuga Tashiro v Hiromasa Oku | 6-3,6-2 |
| ITF Korea F8 | 2016/09/06 02:55 | Young Seok Kim v Hiromasa Oku | 6-0,6-2 |
| ITF Korea F7 | 2016/08/30 06:45 | Hiromasa Oku v Jeamoon Lee | 3-6,6-7 |
| ITF Korea F8 | 2016/08/22 02:30 | Jung-Woong Na v Hiromasa Oku | 4-6,6-1,6-0 |
| ITF Vietnam F8 | 2016/08/01 02:00 | Hiromasa Oku v Sora Fukuda | 2-6,3-6 |
| ITF Vietnam F8 | 2016/07/30 05:30 | Hiromasa Oku v Ansu Bhuyan | 5-7,6-4,7-5 |
| ITF Japan F8 | 2016/06/15 04:30 | Kazuki Nishiwaki v Hiromasa Oku | 2-6,6-3,6-4 |
| ITF Japan F5 | 2017/04/01 02:00 | Yuichiro Inui v Naoki Tajima | 4-6,0-6 |
| ITF Japan F4 | 2017/03/29 05:40 | Naoki Tajima v Yusuke Takahashi | 6-3,1-6,4-6 |
| Challenger Kyoto Qual | 2017/02/18 04:20 | Evgeny Karlovskiy v Naoki Tajima | 6-3,6-1 |
| ITF Japan F1 | 2016/03/05 03:00 | Tung-Lin Wu v Naoki Tajima | 6-4,5-7,6-4 |