Stadium: Centre Court Round: 26 Ground: Hardcourt outdoor
| Challenger Kobe | 2018/11/10 07:20 | Seita Watanabe v Takashi Saito | 4-6,7-5,7-6 |
| ITF M15 Hua Hin | 2019/09/04 03:00 | Arjun Kadhe v Seita Watanabe | 2-6,2-6 |
| ITF M15 Hua Hin | 2019/09/03 08:55 | Aaron Schmid v Seita Watanabe | 3-6,3-6 |
| ITF M15 Hua Hin | 2019/09/02 06:35 | Seita Watanabe v Cameron Green | 6-2,2-6,10-7 |
| ITF M15 Hua Hin | 2019/08/27 08:45 | Billy Harris v Seita Watanabe | 6-2,6-1 |
| ITF M15 Hua Hin | 2019/08/27 05:45 | Bingyu Yu v Seita Watanabe | 2-6,2-6 |
| ITF M15 Hua Hin | 2019/08/21 04:50 | Seong Chan Hong v Seita Watanabe | 6-1,6-2 |
| ITF M15 Hua Hin | 2019/08/20 03:00 | Anirudh Chandrasekar v Seita Watanabe | 2-6,3-6 |
| ITF M15 Hua Hin | 2019/08/19 04:45 | Bang Shuo Yin v Seita Watanabe | 6-4,1-6,5-10 |
| ITF M15 Hua Hin | 2019/09/04 07:35 | Takashi Saito v Yuttana Charoenphon | 5-7,6-4,6-0 |
| ITF M15 Hua Hin | 2019/09/03 04:00 | Takashi Saito v Wei-De Lin | 7-6,6-3 |
| ITF M15 Hua Hin | 2019/09/02 05:20 | Takashi Saito v Chayanon Kaewsuto | 6-3,6-2 |
| ITF M15 Hua Hin | 2019/09/01 02:00 | Yu Hsiou Hsu v Takashi Saito | 6-0,3-6,6-4 |
| ITF M15 Hua Hin | 2019/08/30 03:00 | Takashi Saito v Dayne Kelly | 1-6,6-3,6-4 |
| ITF M15 Hua Hin | 2019/08/28 03:00 | Takashi Saito v Chien Hsun Lo | 6-1,6-1 |
| ITF M15 Jakarta | 2019/08/13 07:00 | Tsung-Hao Huang v Takashi Saito | 6-2,6-7,10-6 |
| ITF M15 Jakarta | 2019/08/12 02:30 | Muhammad Ali Akbar Ramadhani v Takashi Saito | 0-6,0-6 |