Ground: Hardcourt outdoor
| ITF Thailand F9 | 2015/06/21 03:00 | Issei Okamura v Tortrakul, Teeradon | 6-7,6-4,6-1 |
| ITF Thailand F9 | 2015/06/14 04:25 | Issei Okamura v Itzstein, Zach | 6-3,5-7,5-7 |
| ITF Japan F6 | 2015/06/11 01:00 | Issei Okamura v Duckhee Lee | 1-6,4-6 |
| ITF Japan F6 | 2015/06/09 04:00 | Sano, Koichi v Issei Okamura | 2-6,4-6 |
| ITF Japan F6 Qual | 2015/06/08 01:00 | Yuichiro Inui v Issei Okamura | 3-6,1-6 |
| ITF Japan F5 | 2015/06/01 04:10 | Issei Okamura v Tanuma, Ryota | 6-7,4-6 |
| ITF Japan F5 | 2015/05/30 01:00 | Issei Okamura v Iino, Shota | 6-3,2-6,6-4 |
| ITF Thailand F9 | 2015/05/06 06:35 | Hochwalt, Tyler v Issei Okamura | 6-3,1-6,6-2 |
| ITF Thailand F9 | 2015/06/17 03:30 | Onishi, Ken v Sekiguchi, Shuichi | 3-6,3-6 |
| ITF Thailand F9 | 2015/06/16 05:00 | Itzstein, Zach v Onishi, Ken | 6-4,2-6,0-6 |
| ITF China F6 | 2015/06/04 02:00 | Onishi, Ken v Giraldi Requena, Marcos | 4-6,4-6 |
| ITF China F6 | 2015/06/02 06:00 | Onishi, Ken v Wang, Aoxiong | 7-6,6-4 |
| ITF China F6 | 2015/05/26 02:00 | Onishi, Ken v Kim, Young Seok | 3-6,5-7 |
| ITF China F6 Qual | 2015/05/24 02:00 | Onishi, Ken v Aoran Wang | 6-4,6-4 |
| ITF Thailand F9 | 2015/04/28 05:15 | Christopher O'Connell v Onishi, Ken | 7-6,6-2 |
| ITF Thailand F9 | 2015/04/26 06:00 | Kaewsuto, Chayanon v Onishi, Ken | 6-4,1-6,2-6 |