| Challenger Ho Chi Minh City Qual | 10/10 04:45 | 54 | Sekiguchi, Shuichi v Yunseong Chung | 6-4,4-6,6-4 | |
| Challenger Ho Chi Minh City Qual | 10/09 08:20 | 46 | Sekiguchi, Shuichi v Tran, Hoang Anh Khoa | 6-2,6-0 | |
| ATP Chengdu Qual | 09/24 05:00 | 45 | Sekiguchi, Shuichi v Hiroki Moriya | 6-4,3-6,5-7 | |
| Nanchang, China | 09/12 02:00 | 25 | Tatsuma Ito v Sekiguchi, Shuichi | 6-3,1-6,7-6 | |
| Challenger Nanchang Qual | 09/11 03:00 | 54 | Sekiguchi, Shuichi v Nedunchezhiyan, Jeevan | 6-4,6-2 | |
| Challenger Nanchang Qual | 09/10 07:10 | 46 | Sekiguchi, Shuichi v Numajiri, Keisuke | 6-0,6-2 | |
| Challenger Shanghai | 09/08 01:10 | 25 | Sekiguchi, Shuichi v Kavcic, Blaz | 5-7,3-6 | |
| Challenger Shanghai Qual | 09/05 02:00 | 54 | Edan Leshem v Sekiguchi, Shuichi | 4-6,4-6 | |
| Challenger Shanghai Qual | 09/04 03:45 | 46 | Qi, Xi v Sekiguchi, Shuichi | 4-6,2-6 | |
| Challenger Bangkok 4 | 08/30 09:15 | 25 | Sekiguchi, Shuichi v Zhe Li | 6-7,3-6 | |
| Challenger Astana 2 | 07/25 09:25 | 25 | Sekiguchi, Shuichi v Jankovic, Miki | 1-6,2-6 | |
| ITF Japan F6 | 06/04 01:00 | 28 | Sekiguchi, Shuichi v Yasutaka Uchiyama | 3-6,3-6 | |
| ITF Japan F6 | 06/03 03:15 | 27 | Ito, Yuichi v Sekiguchi, Shuichi | 1-6,2-6 | |
| ITF Japan F6 | 06/01 01:00 | 26 | Song, Evan v Sekiguchi, Shuichi | 3-6,1-6 | |
| ITF Japan F6 | 05/31 07:40 | 25 | Kishi, Ryota v Sekiguchi, Shuichi | 3-6,2-6 | |
| ITF Guam F1 | 05/29 02:00 | 29 | Whittington, Andrew v Sekiguchi, Shuichi | 7-6,7-6 | |
| ITF Guam F1 | 05/28 01:35 | 28 | Shiga, Masato v Sekiguchi, Shuichi | 4-6,6-7 | |
| ITF Guam F1 | 05/27 05:45 | 27 | Kikuchi, Gengo v Sekiguchi, Shuichi | 6-7,6-7 | |
| ITF Guam F1 | 05/24 03:45 | 25 | Brooklyn, Matthew v Sekiguchi, Shuichi | 4-6,1-6 | |
| ITF China F7 | 05/20 04:00 | 27 | Sekiguchi, Shuichi v Soonwoo Kwon | 1-6,7-6,3-6 | |
| ITF China F7 | 05/19 02:00 | 26 | Sekiguchi, Shuichi v Song, Evan | 6-7,6-4,6-1 | |
| ITF China F7 | 05/17 02:00 | 25 | Sekiguchi, Shuichi v Bourchier, Harry | 6-3,2-6,6-4 | |
| ITF China F5 | 04/17 03:00 | 29 | Barrientos, Nicolas v Sekiguchi, Shuichi | 6-4,6-1 | |
| ITF China F5 | 04/16 04:35 | 28 | Sekiguchi, Shuichi v Wang, Chuhan | 6-1,7-5 | |
| ITF China F5 | 04/15 03:15 | 27 | Ouyang, Bowen v Sekiguchi, Shuichi | 4-6,4-6 | |
| ITF China F5 | 04/14 03:00 | 26 | Issei Okamura v Sekiguchi, Shuichi | 2-6,2-6 | |
| ITF China F5 | 04/12 07:35 | 25 | Wei-De Lin v Sekiguchi, Shuichi | 1-6,0-6 | |
| ITF China F4 | 04/09 05:20 | 27 | Sekiguchi, Shuichi v Balaji, N. Sriram | 6-3,3-6,5-7 | |
| ITF China F4 | 04/08 04:00 | 26 | Sekiguchi, Shuichi v Xia, Zihao | 6-1,6-1 | |
| ITF China F4 | 04/05 02:00 | 25 | Sekiguchi, Shuichi v Fajing Sun | 6-4,6-0 |