Stadium: Court 7 Round: 44 Ground: Hardcourt outdoor
| ITF Japan F2 | 2016/03/12 00:30 | Numajiri, Keisuke v Watanuki, Keisuke | 6-2,2-6,1-6 |
| ITF Japan F8 | 2015/06/25 01:00 | Numajiri, Keisuke v Watanuki, Keisuke | 3-6,3-6 |
| Challenger Kyoto Qual | 2018/02/17 01:00 | Watanuki, Keisuke v Shibano, Kosuke | 4-6,4-6 |
| ITF Japan F8 | 2017/06/15 02:30 | Watanuki, Keisuke v Ehara, Hiroyasu | 1-6,3-6 |
| ITF Japan F8 | 2017/06/14 05:50 | Kishi, Ryota v Watanuki, Keisuke | 0-6,1-6 |
| ITF Japan F8 | 2017/06/12 00:00 | Watanuki, Keisuke v Kazuki Nishiwaki | 6-2,6-2 |
| ITF Japan F8 | 2017/06/10 04:00 | Watanuki, Keisuke v Taketo Takamisawa | 4-6,6-2,6-3 |
| ITF Japan F7 | 2017/06/08 01:30 | Watanuki, Keisuke v Takeuchi, Kento (1987) | 3-6,5-7 |
| ITF Japan F6 Qual | 2017/05/29 01:00 | Watanuki, Keisuke v Sakai, Yuto | 6-7,6-7 |
| ITF Japan F6 Qual | 2017/05/28 07:00 | Watanuki, Keisuke v Sakai, Yuto | 6-7,6-7 |
| ITF Japan F1 | 2018/03/04 03:00 | Numajiri, Keisuke v Sasai, Masaki | 1-6,6-3,0-6 |
| Turkey F8, Singles Qualifying | 2018/02/24 09:30 | Numajiri, Keisuke v Davydov, Ivan | 1-6,7-6,5-7 |
| ITF Turkey F7 | 2018/02/17 06:30 | Bogdan Bobrov v Numajiri, Keisuke | 6-3,6-2 |
| ITF Vietnam F3 | 2017/11/21 06:10 | Katayama, Sho v Numajiri, Keisuke | 6-4,6-4 |
| ITF Vietnam F3 | 2017/11/20 04:00 | Lawrence Bataljin v Numajiri, Keisuke | 6-4,2-6,6-3 |
| ITF Vietnam F2 | 2017/11/12 04:00 | Jakub Paul v Numajiri, Keisuke | 6-7,6-4,6-1 |
| ITF Malaysia F3 | 2017/10/29 00:00 | Ito, Yuichi v Numajiri, Keisuke | 6-4,6-2 |
| ITF Malaysia F3 | 2017/10/28 01:00 | Numajiri, Keisuke v Alex Hunt | 6-0,6-1 |