| Masters de Malaisie - Qualif. | 01/07 06:35 | - | Joo Ven Soong v Koki Watanabe | W | 1-2 | |
| Masters de Malaisie - Qualif. | 01/07 03:10 | - | Saensomboonsuk, Tanongsak v Koki Watanabe | W | 0-1 | |
| Korea Masters | 11/22 05:20 | 3 | Jun Peng Zhao v Koki Watanabe | L | 2-1 | |
| Korea Masters | 11/21 07:25 | 4 | Koki Watanabe v Kunlavut Vitidsarn | W | 2-0 | |
| Korea Masters | 11/20 10:20 | 5 | Koki Watanabe v Corvee, Lucas | W | 2-1 | |
| Vietnam Open | 09/12 09:20 | 4 | Koki Watanabe v Sun, F. | L | 0-2 | |
| Vietnam Open | 09/12 02:00 | 5 | Heo, Kwang Hee v Koki Watanabe | W | 1-2 | |
| Vietnam Open | 09/11 02:30 | 6 | Koki Watanabe v Ivancic, Miha | W | 2-0 | |
| Chinese Taipei Open 2019, MS | 09/07 05:00 | 2 | Heo, Kwang Hee v Koki Watanabe | L | 2-1 | |
| Chinese Taipei Open 2019, MS | 09/06 09:00 | 3 | Lu, C. H. v Koki Watanabe | W | 0-2 | |
| Chinese Taipei Open 2019, MS | 09/05 09:15 | 4 | Koki Watanabe v Kean Yew Loh | W | 2-1 | |
| Chinese Taipei Open 2019, MS | 09/04 12:30 | 5 | Yang, Chih Chieh v Koki Watanabe | W | 0-2 | |
| Akita Masters 2019, MS | 08/16 02:15 | 3 | Igarashi, Yu v Koki Watanabe | L | 2-1 | |
| Akita Masters 2019, MS | 08/15 05:25 | 4 | Koki Watanabe v Thongnuam, Pannawit | W | 2-0 | |
| Akita Masters 2019, MS | 08/14 02:10 | 5 | Koki Watanabe v Koga, Minoru | W | 2-0 | |
| US Open 2019, MS | 07/11 22:00 | 4 | Lee, Dong Keun v Koki Watanabe | L | 2-1 | |
| US Open 2019, MS | 07/10 22:10 | 5 | Svendsen, Victor v Koki Watanabe | W | 0-2 | |
| Canada Open | 07/06 21:30 | 2 | Koki Watanabe v Shi Feng Li | L | 1-2 | |
| Canada Open | 07/05 22:00 | 3 | Ouseph, Rajiv v Koki Watanabe | W | 0-2 | |
| Canada Open | 07/04 21:55 | 4 | Lan Xi Lei v Koki Watanabe | W | 1-2 | |
| Canada Open | 07/03 19:00 | 5 | Koki Watanabe v H.S. Prannoy | W | 2-0 | |
| Canada Open | 07/03 00:50 | 6 | Koki Watanabe v Ho-Shue, Jason Anthony | W | 2-0 | |
| Open d'Australie - Qualif. | 06/04 00:10 | - | Sun, F. v Koki Watanabe | L | 2-1 | |
| New Zealand Open Qual | 04/29 22:35 | - | Koki Watanabe v Sun, F. | L | 0-2 | |
| Osaka Int. | 04/07 02:00 | - | Takuma Obayashi v Koki Watanabe | W | 1-2 | |
| Osaka Int. | 04/06 04:30 | - | Koki Watanabe v Ren, P. B. | W | 2-0 | |
| Osaka Int. | 04/04 06:40 | - | Weng, H. Y. v Koki Watanabe | W | 0-2 | |
| Orléans Masters | 03/24 14:00 | 1 | Koki Watanabe v Rouxel, Thomas | W | 2-1 | |
| Orléans Masters | 03/23 14:30 | 2 | Koki Watanabe v Li, S. F. | W | 2-0 | |
| Orléans Masters | 03/22 15:40 | 3 | Cupu, G. P. F. v Koki Watanabe | W | 0-2 |