Stadium: Court 10 Round: 26 Ground: Hardcourt outdoor
| ITF - M25 Mildura | 2019/03/07 02:00 | Issei Okamura v Sekiguchi, Shuichi | 3-6,6-3,2-6 |
| ITF China F5 | 2016/04/14 03:00 | Issei Okamura v Sekiguchi, Shuichi | 2-6,2-6 |
| Matsuyama, Singles M-ITF-JPN-06A | 2019/04/10 07:00 | Jumpei Yamasaki v Issei Okamura | 6-4,5-7,1-6 |
| Matsuyama, Singles M-ITF-JPN-06A | 2019/04/09 02:40 | Issei Okamura v Iino, Shota | 6-2,6-2 |
| ITF - M15 Kashiwa | 2019/04/04 01:00 | Issei Okamura v Jumpei Yamasaki | 3-6,2-6 |
| ITF - M15 Kashiwa | 2019/04/02 05:50 | Taisei Ichikawa v Issei Okamura | 7-5,5-7,5-7 |
| ITF - M15 Tsukuba | 2019/03/27 03:25 | Issei Okamura v Naoki Tajima | 3-6,4-6 |
| Kofu, Qualifications Simples M-ITF-JPN-03A | 2019/03/22 02:00 | Issei Okamura v Tanuma, Ryota | 4-6,2-6 |
| Kofu, Qualifications Simples M-ITF-JPN-03A | 2019/03/21 02:00 | Takuya Kumasaka v Issei Okamura | 1-6,2-6 |
| Kofu, Qualifications Simples M-ITF-JPN-03A | 2019/03/19 02:50 | Aoran Wang v Issei Okamura | 2-6,6-4,4-6 |
| Matsuyama, Singles M-ITF-JPN-06A | 2019/04/09 04:10 | Tanuma, Ryota v Sekiguchi, Shuichi | 4-6,4-6 |
| ITF - M15 Kashiwa | 2019/04/03 05:20 | Niki, Takuto v Sekiguchi, Shuichi | 2-6,6-3,7-6 |
| ITF - M15 Nishi-Tokyo | 2019/03/17 02:00 | Sekiguchi, Shuichi v Hong, Seong Chan | 6-7,4-6 |
| ITF - M15 Nishi-Tokyo | 2019/03/16 01:00 | Niki, Takuto v Sekiguchi, Shuichi | 4-6,7-6,3-6 |
| ITF - M15 Nishi-Tokyo | 2019/03/15 01:00 | Sekiguchi, Shuichi v Shintaro Imai | 6-3,6-0 |
| ITF - M15 Nishi-Tokyo | 2019/03/14 03:45 | Sekiguchi, Shuichi v Yuki Mochizuki | 6-2,6-1 |
| ITF - M15 Nishi-Tokyo | 2019/03/13 01:00 | Sekiguchi, Shuichi v Keisuke Saitoh | 6-3,6-2 |
| ITF - M25 Mildura | 2019/03/09 01:00 | Sekiguchi, Shuichi v Klein, Brydan | 7-6,1-6,1-6 |