| ITF Chinese Taipei F1 | 06/13 03:25 | 25 | Tung-Lin Wu v Sekiguchi, Shuichi | 6-4,6-2 | |
| ITF Japan F7 | 06/09 01:00 | 27 | Yosuke Watanuki v Sekiguchi, Shuichi | 6-4,5-7,6-0 | |
| ITF Japan F7 | 06/07 06:40 | 26 | Matsuo, Yuki v Sekiguchi, Shuichi | 4-6,2-6 | |
| ITF Japan F7 | 06/05 04:10 | 25 | Ehara, Hiroyasu v Sekiguchi, Shuichi | 2-6,1-6 | |
| ITF Japan F6 | 05/31 01:00 | 26 | Kikuchi, Gengo v Sekiguchi, Shuichi | 6-4,6-2 | |
| ITF Japan F6 | 05/29 05:55 | 25 | Yuki Mochizuki v Sekiguchi, Shuichi | 3-6,4-6 | |
| Challenger Seoul | 05/09 04:00 | 25 | Duckhee Lee v Sekiguchi, Shuichi | 6-0,6-3 | |
| Challenger Seoul Qual | 05/08 02:00 | 54 | [435] Glasspool, Lloyd v Sekiguchi, Shuichi [319] | 3-6,3-6 | |
| Challenger Seoul Qual | 05/07 04:20 | 46 | [404] Makoto Ochi v Sekiguchi, Shuichi [319] | 1-6,1-6 | |
| Challenger Seoul Qual | 05/06 06:05 | 45 | Kim, Yu-Seob v Sekiguchi, Shuichi | 1-6,4-6 | |
| Challenger - Taipei | 04/18 06:20 | 25 | [305] Sekiguchi, Shuichi v Skugor, Franko [323] | 1-6,4-6 | |
| ITF China F5 | 04/15 05:35 | 28 | [438] Mousley, Bradley v Sekiguchi, Shuichi [326] | 7-6,7-6 | |
| ITF China F5 | 04/14 04:50 | 27 | [451] Kapas, Andriej v Sekiguchi, Shuichi [326] | Retired | |
| ITF China F5 | 04/13 05:05 | 26 | [239] Yang, Tsung-Hua v Sekiguchi, Shuichi [326] | 2-6,4-6 | |
| ITF China F5 | 04/11 06:50 | 25 | Chang, Yu v Sekiguchi, Shuichi | 1-6,5-7 | |
| ITF China F4 | 04/09 02:00 | 29 | [266] Li, Zhe v Sekiguchi, Shuichi [325] | 6-3,6-0 | |
| ITF China F4 | 04/08 04:00 | 28 | Zhong, Su Hao v Sekiguchi, Shuichi | 1-6,6-2,2-6 | |
| ITF China F4 | 04/07 02:30 | 27 | Wang, Jimmy v Sekiguchi, Shuichi | Retired | |
| ITF China F4 | 04/06 05:05 | 26 | Qi, Xi v Sekiguchi, Shuichi | 4-6,3-6 | |
| ITF China F4 | 04/04 05:50 | 25 | Chen, Long v Sekiguchi, Shuichi | 0-6,0-6 | |
| Challenger Quanzhou | 03/23 04:50 | 26 | [324] Sekiguchi, Shuichi v Ignatik, Uladzimir [147] | 6-7,4-6 | |
| Challenger Quanzhou | 03/20 02:05 | 25 | [190] Velotti, Agustin v Sekiguchi, Shuichi [324] | 6-7,4-6 | |
| Quanzhou, China, Qualifying | 03/19 03:40 | 54 | [324] Sekiguchi, Shuichi v Andrea Pellegrino [475] | 2-6,6-7 | |
| Quanzhou, China, Qualifying | 03/18 05:00 | 46 | [324] Sekiguchi, Shuichi v Bury, Aliaksandr [89] | 6-2,6-0 | |
| Shenzhen, China, Qualifying | 03/12 09:00 | 46 | [474] Kuan-Yi Lee v Sekiguchi, Shuichi [324] | 6-3,6-4 | |
| Shenzhen, China, Qualifying | 03/12 04:45 | 45 | [324] Sekiguchi, Shuichi v Jaume Munar [247] | 6-4,2-6,6-3 | |
| Challenger Zhuhai Qual | 03/06 06:30 | 54 | [321] Sekiguchi, Shuichi v Lorenzo Sonego [310] | 3-6,4-6 | |
| Challenger Zhuhai Qual | 03/05 08:00 | 46 | Marc Polmans v Sekiguchi, Shuichi | 2-6,4-6 | |
| Challenger Zhuhai Qual | 03/04 05:20 | 45 | Yu, Cheng-Yu v Sekiguchi, Shuichi | 6-3,4-6,6-7 | |
| Yokohama, Japan, Qualifying | 02/27 01:00 | 54 | Klein, Brydan v Sekiguchi, Shuichi | 7-5,6-2 |