Round: 25 Ground: Synthetic outdoor
| ITF Japan F1 | 2016/03/10 02:35 | Niki, Takuto v Watanuki, Keisuke | 7-5,6-2 |
| ITF Japan F6 | 2015/06/11 02:55 | Niki, Takuto v Watanuki, Keisuke | 6-7,7-6,6-4 |
| ITF Japan F3 | 2014/03/26 02:50 | Niki, Takuto v Watanuki, Keisuke | 6-3,6-1 |
| ITF Japan F6 | 2016/05/31 05:25 | Yusuke Takahashi v Watanuki, Keisuke | 6-3,6-4 |
| ITF Japan F6 Qual | 2016/05/29 04:00 | Watanuki, Keisuke v Sho Shimabukuro | 6-1,6-0 |
| ITF Japan F6 Qual | 2016/05/28 01:00 | Watanuki, Keisuke v Yoshida, Shin | 6-1,6-4 |
| ITF Japan F5 | 2016/04/06 03:40 | Watanuki, Keisuke v Katayama, Sho | 2-6,5-7 |
| ITF Japan F4 | 2016/03/29 05:10 | Watanuki, Keisuke v Shintaro Imai | 3-6,6-3,1-6 |
| ITF Japan F4 | 2016/03/28 01:00 | Kikuchi, Gengo v Watanuki, Keisuke | 2-6,7-5,6-7 |
| ITF Japan F4 | 2016/03/27 01:00 | Yusuke Takahashi v Watanuki, Keisuke | 4-6,3-6 |
| ITF Japan F3 | 2016/03/22 03:10 | Onishi, Ken v Watanuki, Keisuke | 2-6,6-2,7-5 |
| ITF Japan F6 | 2016/05/31 01:00 | Niki, Takuto v Oku, Hiromasa | 2-6,3-6 |
| ITF Guam F1 | 2016/05/27 01:25 | Whittington, Andrew v Niki, Takuto | 4-6,6-4,6-4 |
| ITF Guam F1 | 2016/05/24 06:30 | Oljaca, Mark v Niki, Takuto | 4-6,0-6 |
| ITF Japan F5 | 2016/04/08 06:25 | Niki, Takuto v Katayama, Sho | 7-6,2-6,3-6 |
| ITF Japan F5 | 2016/04/06 03:40 | Niki, Takuto v Ko Suzuki | 6-4,3-6,6-2 |
| ITF Japan F4 | 2016/03/30 01:00 | Niki, Takuto v Ryota Tanuma | 4-6,5-7 |
| ITF Japan F3 | 2016/03/21 03:45 | Gao, Xin v Niki, Takuto | 2-6,6-2,6-2 |
| ITF Japan F2 | 2016/03/15 02:25 | Niki, Takuto v Yunseong Chung | 3-6,6-3,3-6 |