Ground: Hardcourt outdoor
| ITF M15 Hinode | 2024/03/11 04:45 | Seiya Nakanishi v Shunsuke Nakagawa | 4-6,2-6 |
| ITF M15 Hinode | 2024/03/11 01:00 | Jumpei Yamasaki v Seiya Nakanishi | 5-7,6-4,8-10 |
| ITF M15 Yanagawa | 2023/12/25 00:30 | Kazuma Kawachi v Seiya Nakanishi | 6-3,6-0 |
| ITF M25 Takasaki | 2023/09/17 01:00 | Ryotaro Matsumura v Seiya Nakanishi | 6-2,6-4 |
| ITF M25 Sapporo | 2023/09/05 04:15 | Issei Okamura v Seiya Nakanishi | 6-1,6-1 |
| 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 |