| ITF Japan F8 | 06/14 02:50 | 26 | Katayama, Sho v Watanuki, Keisuke | 6-2,6-0 | |
| ITF Japan F8 | 06/12 01:00 | 25 | Watanuki, Keisuke v Uesugi, Teppei | 6-3,6-3 | |
| ITF Japan F8 | 06/11 00:30 | 62 | Watanuki, Keisuke v Daisuke Sumizawa | 6-4,2-6,6-2 | |
| ITF Japan F3 | 03/17 00:30 | 44 | Watanuki, Keisuke v Numajiri, Keisuke | 3-6,1-6 | |
| Challenger Kyoto Qual | 02/17 01:00 | 45 | Watanuki, Keisuke v Shibano, Kosuke | 4-6,4-6 | |
| ITF Japan F8 | 06/15 02:30 | 26 | Watanuki, Keisuke v Ehara, Hiroyasu | 1-6,3-6 | |
| ITF Japan F8 | 06/14 05:50 | 25 | Kishi, Ryota v Watanuki, Keisuke | 0-6,1-6 | |
| ITF Japan F8 | 06/12 00:00 | 62 | Watanuki, Keisuke v Kazuki Nishiwaki | 6-2,6-2 | |
| ITF Japan F8 | 06/10 04:00 | 62 | Watanuki, Keisuke v Taketo Takamisawa | 4-6,6-2,6-3 | |
| ITF Japan F7 | 06/08 01:30 | 26 | Watanuki, Keisuke v Takeuchi, Kento (1987) | 3-6,5-7 | |
| ITF Japan F7 | 06/06 04:40 | 25 | Watanuki, Keisuke v Tung-Lin Wu | Retired | |
| ITF Japan F6 Qual | 05/29 01:00 | 54 | Watanuki, Keisuke v Sakai, Yuto | 6-7,6-7 | |
| ITF Japan F6 Qual | 05/28 07:00 | - | Watanuki, Keisuke v Sakai, Yuto | 6-7,6-7 | |
| ITF Japan F6 Qual | 05/27 01:00 | 54 | Watanuki, Keisuke v Han, Sung Min | 6-4,6-0 | |
| ITF Japan F5 | 04/02 01:00 | 54 | Sasai, Masaki v Watanuki, Keisuke | 6-2,6-4 | |
| ITF Japan F5 | 04/01 02:00 | 54 | Yasugami, Takashi v Watanuki, Keisuke | 4-6,6-2,5-7 | |
| ITF Japan F4 | 03/28 01:00 | 62 | Masaya Kobayashi v Watanuki, Keisuke | 6-3,6-2 | |
| ITF Japan F4 | 03/27 01:00 | 62 | Tashiro, Yuga v Watanuki, Keisuke | 2-6,6-7 | |
| ITF Japan F4 | 03/25 03:00 | 62 | Chang, Yu v Watanuki, Keisuke | 7-6,3-6,4-6 | |
| ITF Japan F2 | 03/14 04:20 | 25 | Yusuke Takahashi v Watanuki, Keisuke | 6-2,6-2 | |
| ITF Japan F2 | 03/13 01:00 | 44 | Wachiramanowong, Kittipong v Watanuki, Keisuke | 4-6,6-7 | |
| ITF Japan F2 | 03/12 02:00 | 44 | Watanuki, Keisuke v Fujii, Shinta | 6-2,2-6,6-2 | |
| ITF Japan F2 | 03/11 03:00 | 44 | Kawahashi, Yuta v Watanuki, Keisuke | 2-6,2-6 | |
| ITF Japan F1 | 03/06 01:00 | 62 | Itsusaki, Kaito v Watanuki, Keisuke | 6-3,6-3 | |
| ITF Japan F1 | 03/05 01:00 | 62 | Osafune, Masaki v Watanuki, Keisuke | 6-7,6-0,2-6 | |
| ITF Japan F8 | 06/16 02:15 | 26 | Watanuki, Keisuke v Katayama, Sho | 3-6,1-6 | |
| ITF Japan F8 | 06/15 04:30 | 25 | Takeshima, Shunrou v Watanuki, Keisuke | 6-7,0-6 | |
| ITF Japan F7 | 06/09 02:30 | 26 | Oh, Chan-Yeong v Watanuki, Keisuke | 6-3,6-7,6-4 | |
| ITF Japan F7 | 06/07 01:00 | 25 | Watanuki, Keisuke v Niki, Takuto | 6-4,7-6 | |
| ITF Japan F6 | 05/31 05:25 | 25 | Yusuke Takahashi v Watanuki, Keisuke | 6-3,6-4 |