Stadium: Court 9 Round: 25 Ground: Hardcourt outdoor
| ITF M25 Tsukuba | 2023/03/27 00:30 | Seiya Nakanishi v Issei Okamura | 2-6,4-6 |
| ITF M25 Sapporo | 2023/09/04 00:55 | Issei Okamura v Shinnosuke Hiramatsu | 7-5,6-4 |
| ITF M25 Tainan | 2023/08/16 02:00 | Ergi Kirkin v Issei Okamura | 6-0,6-2 |
| ITF M25 Herzlia | 2023/08/09 11:25 | Amit Vales v Issei Okamura | 6-4,3-6,6-3 |
| ITF M25 Herzlia | 2023/08/08 06:30 | Issei Okamura v Eyal Shyovitz | 6-4,6-3 |
| ITF M25 Herzlia | 2023/08/07 06:30 | Issei Okamura v Raz Katz | 6-1,6-1 |
| ITF M15 Raanana | 2023/08/01 13:20 | Issei Okamura v Ofek Shimanov | 6-4,3-6,2-6 |
| ITF M15 Jakarta | 2023/06/27 05:00 | Koki Matsuda v Issei Okamura | 6-3,7-6 |
| ITF M25 Anseong | 2023/06/21 02:00 | Sanhui Shin v Issei Okamura | 6-2,6-3 |
| ITF M25 Sapporo | 2023/09/04 03:35 | Ryusuke Horiuchi v Seiya Nakanishi | 6-4,2-6,10-12 |
| ITF M15 Karuizawa | 2023/05/28 01:15 | Seiya Nakanishi v Yua Taka | 4-6,2-6 |
| ITF M25 Kashiwa | 2023/04/02 00:30 | Jeremy Jin v Seiya Nakanishi | 6-3,6-2 |
| ITF M25 Tsukuba | 2023/03/27 00:30 | Seiya Nakanishi v Issei Okamura | 2-6,4-6 |
| Challenger Yokohama | 2022/10/30 02:35 | Seiya Nakanishi v Daisuke Sumizawa | 3-6,0-6 |
| ITF M25 Sapporo | 2022/09/01 02:50 | Rio Noguchi v Seiya Nakanishi | 6-0,6-3 |