Ground: Synthetic outdoor
| ITF Japan F8 | 2014/06/27 01:00 | Watanuki, Keisuke v Onozawa, Arata | 3-6,4-6 |
| ITF Japan F5 | 2015/06/02 01:00 | 越智 真 v Onozawa, Arata | 3-6,6-2,6-4 |
| ITF China F6 | 2015/05/26 07:20 | Onozawa, Arata v Gong, Peng-Xiang | 6-0,6-2 |
| ITF China F6 | 2015/05/20 02:00 | Onozawa, Arata v シ,シ | 4-6,1-6 |
| ITF Thailand F9 | 2015/05/06 03:00 | Onozawa, Arata v Burapharitta, Phassawit | 6-2,0-6,5-7 |
| ITF Thailand F9 | 2015/05/05 04:25 | Onozawa, Arata v 越智 真 | 6-3,6-3 |
| ITF Thailand F9 | 2015/04/29 04:55 | Sornbutnark, Warit v Onozawa, Arata | 6-3,6-2 |
| ITF Thailand F9 | 2015/04/28 07:15 | Shiga, Masato v Onozawa, Arata | 3-6,6-7 |
| ITF Japan F4 | 2015/03/30 05:00 | Onozawa, Arata v 関口 周一 | 4-6,4-6 |
| ITF Japan F6 | 2015/06/11 02:55 | 仁木 拓人 v Watanuki, Keisuke | 6-7,7-6,6-4 |
| ITF Japan F6 | 2015/06/10 01:30 | Watanuki, Keisuke v Oku, Hiromasa | 6-2,6-3 |
| ITF Japan F5 | 2015/06/04 02:00 | トーマス・ファンカット v Watanuki, Keisuke | 7-5,7-6 |
| ITF Japan F5 | 2015/06/03 06:30 | 松村 亮太朗 v Watanuki, Keisuke | 6-2,4-6,0-6 |
| ITF Greece F9 | 2015/04/29 10:05 | Simunek, David v Watanuki, Keisuke | 6-4,6-2 |
| ITF Greece F5 | 2015/04/23 07:00 | トム・コセバー＝デスマン v Watanuki, Keisuke | 6-3,6-2 |
| ITF Greece F5 | 2015/04/21 10:40 | Kapogiannis, Charalampos v Watanuki, Keisuke | 6-3,1-6,5-7 |
| ITF Greece F4 | 2015/04/12 11:00 | Watanuki, Keisuke v ステファン・フルジャニック | 6-4,2-6,5-7 |