Round: 25 Ground: Hardcourt outdoor
| ITF Japan F2 | 2016/03/12 02:00 | Tung-Lin Wu v Onishi, Ken | 6-2,6-2 |
| ITF Kuwait F3 | 2015/11/26 08:00 | Onishi, Ken v Evgeny Karlovskiy | 3-6,2-6 |
| ITF Kuwait F3 | 2015/11/25 12:30 | Onishi, Ken v Ghareeb, Ali | 6-3,6-2 |
| ITF Kuwait F3 | 2015/11/23 10:15 | Martos Gornes, Sergio v Onishi, Ken | 4-6,1-6 |
| ITF Kuwait F2 | 2015/11/18 09:00 | Onishi, Ken v Monteban, Paul | 6-7,6-7 |
| ITF Kuwait F2 | 2015/11/16 07:00 | Micov, Stefan v Onishi, Ken | 4-6,1-6 |
| ITF Turkey F36 | 2015/10/07 07:00 | Onishi, Ken v Fabian, Patrik | 4-6,6-3,3-6 |
| ITF Turkey F38 | 2015/09/25 13:30 | Peter Heller v Onishi, Ken | 6-1,6-2 |
| ITF Japan F3 | 2016/03/20 02:30 | Shiga, Masato v Watanuki, Keisuke | 4-6,6-2,3-6 |
| ITF Japan F3 | 2016/03/19 03:45 | Rigele Te v Watanuki, Keisuke | 2-6,1-6 |
| ITF Japan F2 | 2016/03/15 04:30 | Watanuki, Keisuke v Kibi, Yuya | 2-6,6-4,1-6 |
| ITF Japan F2 | 2016/03/13 01:00 | Aoran Wang v Watanuki, Keisuke | 0-6,4-6 |
| ITF Japan F2 | 2016/03/12 00:30 | Numajiri, Keisuke v Watanuki, Keisuke | 6-2,2-6,1-6 |
| ITF Japan F1 | 2016/03/10 02:35 | Niki, Takuto v Watanuki, Keisuke | 7-5,6-2 |
| ITF Japan F1 | 2016/03/07 01:00 | Watanuki, Keisuke v Kazuma Kawachi | 6-1,6-1 |
| ITF Japan F1 | 2016/03/06 03:00 | Watanuki, Keisuke v Sora Fukuda | 6-1,3-6,6-3 |