Ground: Hardcourt outdoor
| ITF M25 Takasaki | 2024/09/15 01:00 | Seiya Nakanishi v Noritaka Koizumi | 5-7,4-6 |
| ITF M25 Sapporo | 2024/09/09 03:30 | Shunsuke Nakagawa v Seiya Nakanishi | 6-2,6-2 |
| ITF M25 Sapporo | 2024/09/08 01:00 | Yusuke Yoshikawa v Seiya Nakanishi | 7-6,6-7,7-10 |
| ITF M25 Sapporo | 2024/09/02 02:35 | Brandon Perez v Seiya Nakanishi | 7-5,6-1 |
| UTR Pro Kawaguchi | 2024/08/18 00:00 | Seiya Nakanishi v Kazuki Sugimoto | 3-6,2-6 |
| UTR Pro Kawaguchi | 2024/08/17 00:00 | Sora Fukuda v Seiya Nakanishi | 3-6,0-6 |
| UTR Pro Kawaguchi | 2024/08/15 07:43 | Daisuke Sumizawa v Seiya Nakanishi | 6-2,6-3 |
| UTR Pro Kawaguchi | 2024/08/15 01:00 | Christopher Kosei Ono v Seiya Nakanishi | 6-7,5-7 |