Stadium: Court 1 Round: 25 Ground: Hardcourt outdoor
| Kofu, Qualifications Simples M-ITF-JPN-03A | 2019/03/22 02:00 | Issei Okamura v Tanuma, Ryota | 4-6,2-6 |
| ITF China F1 | 2018/01/11 02:30 | Tanuma, Ryota v Issei Okamura | 6-1,6-2 |
| ITF China F13 | 2016/07/22 05:20 | Tanuma, Ryota v Issei Okamura | 3-6,6-7 |
| ITF Spain F14 | 2016/05/16 09:00 | Issei Okamura v Tanuma, Ryota | 0-6,3-6 |
| ITF Chinese Taipei F1 | 2015/08/21 02:00 | Issei Okamura v Tanuma, Ryota | 6-4,3-6,6-3 |
| ITF Japan F5 | 2015/06/01 04:10 | Issei Okamura v Tanuma, Ryota | 6-7,4-6 |
| ITF - M15 Sharm El Sheikh | 2020/02/25 08:00 | Issei Okamura v Nguyen, Phuong van | 6-3,4-6,10-6 |
| ITF - M15 Sharm El Sheikh | 2020/02/24 09:00 | Issei Okamura v Mzai, Ismael Changawa Ruwa | 6-3,3-6,10-5 |
| ITF - M15 Sharm El Sheikh | 2020/02/20 09:40 | Issei Okamura v Jacopo Berrettini | 1-6,2-6 |
| ITF - M15 Sharm El Sheikh | 2020/02/19 15:40 | Issei Okamura v Piotr Grynkowski | 6-3,7-5 |
| Nonthaburi, Singles M-ITF-THA-01A | 2020/01/26 07:50 | Issei Okamura v Kovapitukted, Palaphoom | 4-6,1-6 |
| Hong Kong, Simples M-ITF-HKG-01A | 2020/01/08 06:50 | El Midhawy, Adam v Issei Okamura | 4-6,6-2,6-3 |
| Hong Kong, Simples M-ITF-HKG-01A | 2020/01/07 02:00 | Issei Okamura v Kaewsuto, Chayanon | 6-0,6-0 |
| Hong Kong, Simples M-ITF-HKG-01A | 2020/01/06 02:00 | Issei Okamura v Geiwald, Douglas | 6-2,6-1 |
| ITF - M15 Sharm El Sheikh | 2020/02/19 12:00 | Daniil Glinka v Tanuma, Ryota | 6-2,6-2 |
| Challenger Launceston | 2020/02/05 05:05 | Tanuma, Ryota v Liam Broady | 3-6,2-6 |
| Challenger Launceston | 2020/02/03 23:00 | Tanuma, Ryota v Tristan Schoolkate | 6-2,6-3 |
| Challenger Launceston | 2020/02/02 23:00 | Naoki Tajima v Tanuma, Ryota | 6-2,6-2 |
| Hong Kong, Simples M-ITF-HKG-01A | 2020/01/09 03:25 | Makoto Ochi v Tanuma, Ryota | 6-4,6-4 |
| Hong Kong, Simples M-ITF-HKG-01A | 2020/01/08 09:00 | Tanuma, Ryota v Hanyi Liu | 6-2,6-3 |
| Nonthaburi, Simples M-ITF-THA-06A | 2019/11/27 02:30 | Keisuke Saitoh v Tanuma, Ryota | 6-2,7-6 |
| Challenger Kobe | 2019/11/05 04:15 | Jay Clarke v Tanuma, Ryota | 6-3,3-6,6-3 |