| ITF Japan F3 | 03/25 03:00 | 28 | Duckhee Lee v Sekiguchi, Shuichi | 7-5,6-3 | |
| ITF Japan F3 | 03/24 03:15 | 27 | Kim, Young Seok v Sekiguchi, Shuichi | 2-6,0-6 | |
| ITF Japan F3 | 03/23 01:00 | 26 | Ito, Yuya v Sekiguchi, Shuichi | 5-7,4-6 | |
| ITF Japan F3 | 03/22 03:30 | 25 | Ryota Tanuma v Sekiguchi, Shuichi | 6-4,1-6,2-6 | |
| ITF Japan F2 | 03/18 03:20 | 27 | Sekiguchi, Shuichi v Masaya Kobayashi | 3-6,2-6 | |
| ITF Japan F2 | 03/17 03:20 | 26 | Sekiguchi, Shuichi v Sho Shimabukuro | 6-4,6-2 | |
| ITF Japan F2 | 03/15 03:40 | 25 | Sekiguchi, Shuichi v Sakai, Yuto | 6-3,6-1 | |
| ITF Japan F1 | 03/12 05:30 | 28 | Kikuchi, Gengo v Sekiguchi, Shuichi | 7-6,6-1 | |
| ITF Japan F1 | 03/12 01:00 | 27 | Sekiguchi, Shuichi v Kibi, Yuya | 6-4,6-3 | |
| ITF Japan F1 | 03/10 04:25 | 26 | Sekiguchi, Shuichi v Katayama, Sho | 7-5,7-6 | |
| ITF Japan F1 | 03/10 01:00 | 25 | Sekiguchi, Shuichi v Sasai, Masaki | 6-3,6-0 | |
| Challenger Launceston | 02/02 04:20 | 25 | Alex Bolt v Sekiguchi, Shuichi | 6-3,6-4 | |
| Challenger Shanghai | 10/10 05:40 | 45 | Nikoloz Basilashvili v Sekiguchi, Shuichi | 6-4,6-2 | |
| WTA Kuala Lumpur Qual | 09/26 02:00 | 45 | Begemann, Andre v Sekiguchi, Shuichi | 2-6,6-2,6-3 | |
| Challenger Kaohsiung Qual | 09/20 06:50 | 44 | Sekiguchi, Shuichi v Yi, Chu-Huan | 4-6,4-6 | |
| Challenger Granby | 07/23 15:00 | 26 | Sekiguchi, Shuichi v Donati, Matteo | 4-6,1-6 | |
| ITF Thailand F9 | 06/27 03:00 | - | Rungkat, Christopher v Sekiguchi, Shuichi | 6-4,6-3 | |
| ITF Thailand F9 | 06/26 03:00 | - | Sekiguchi, Shuichi v Na, Jung-Woong | 6-4,6-3 | |
| ITF Thailand F9 | 06/25 03:00 | - | Sekiguchi, Shuichi v Singh, Karunuday | 6-0,6-2 | |
| ITF Thailand F9 | 06/24 05:00 | - | Sekiguchi, Shuichi v Sornbutnark, Warit | 6-4,6-3 | |
| ITF Thailand F9 | 06/22 04:15 | - | Sekiguchi, Shuichi v Kim, Woo-Ram | 6-2,3-6,6-1 | |
| ITF Thailand F9 | 06/20 03:00 | - | Takeuchi, Kento (1987) v Sekiguchi, Shuichi | 1-6,2-6 | |
| ITF Thailand F9 | 06/19 03:00 | - | Toshihide Matsui v Sekiguchi, Shuichi | 4-6,4-6 | |
| ITF Thailand F9 | 06/18 05:05 | - | Rungkat, Christopher v Sekiguchi, Shuichi | Retired | |
| ITF Thailand F9 | 06/17 03:30 | - | Onishi, Ken v Sekiguchi, Shuichi | 3-6,3-6 | |
| ITF Thailand F9 | 06/16 08:10 | - | Bodhidatta, Punn v Sekiguchi, Shuichi | 2-6,1-6 | |
| ITF Japan F6 | 06/10 03:10 | - | Sasai, Masaki v Sekiguchi, Shuichi | 7-6,7-5 | |
| ITF Indonesia F3 | 04/15 03:00 | - | Sekiguchi, Shuichi v Tearney, Finn | 6-7,6-3,6-7 | |
| ITF Indonesia F2 | 04/12 04:00 | - | Duckhee Lee v Sekiguchi, Shuichi | Retired | |
| ITF Indonesia F2 | 04/11 04:00 | - | Tearney, Finn v Sekiguchi, Shuichi | 0-6,1-6 |