| Challenger Kaohsiung | 09/17 12:15 | 25 | [286] Shuichi Sekiguchi v Prajnesh Gunneswaran [82] | 3-6,2-6 | |
| Challenger Kaohsiung | 09/16 06:05 | 24 | Ray Ho v Shuichi Sekiguchi | 6-7,3-6 | |
| Challenger Shanghai | 09/12 06:30 | 26 | [165] Yasutaka Uchiyama v Shuichi Sekiguchi [290] | 6-4,6-3 | |
| Challenger Shanghai | 09/11 06:45 | 25 | [290] Shuichi Sekiguchi v Saketh Myneni [258] | 4-6,6-3,7-6 | |
| Challenger Shanghai | 09/09 06:05 | 24 | [372] Jacob Grills v Shuichi Sekiguchi [304] | 6-3,1-6,1-6 | |
| Challenger Jinan | 09/04 06:30 | 25 | [243] Akira Santillan v Shuichi Sekiguchi [304] | 6-1,6-2 | |
| Challenger Jinan | 09/03 04:55 | 24 | [285] Sasi Kumar Mukund v Shuichi Sekiguchi [304] | 3-6,3-6 | |
| Challenger Yokkaichi | 08/08 04:30 | 26 | [308] Shuichi Sekiguchi v Tung-Lin Wu [286] | Retired | |
| Challenger Yokkaichi | 08/07 05:30 | 25 | [310] Ze Zhang v Shuichi Sekiguchi [308] | 6-3,6-7,5-7 | |
| Challenger Yokkaichi | 08/06 01:00 | 24 | Kosuke Ogura v Shuichi Sekiguchi | 1-6,3-6 | |
| Challenger Chengdu | 08/02 09:15 | 27 | [458] Shuichi Sekiguchi v Tatsuma Ito [154] | 2-6,1-6 | |
| Challenger Chengdu | 08/01 07:45 | 26 | [251] Goncalo Oliveira v Shuichi Sekiguchi [458] | 4-6,6-3,4-6 | |
| Challenger Chengdu | 07/31 08:55 | 25 | [458] Shuichi Sekiguchi v Tsung-Hua Yang [300] | 6-4,6-4 | |
| Challenger Chengdu | 07/29 10:30 | 24 | Wei Qiang Zheng v Shuichi Sekiguchi | 5-7,1-6 | |
| Challenger Nur-Sultan | 07/18 05:00 | 26 | Egor Gerasimov v Shuichi Sekiguchi | 6-2,6-0 | |
| Challenger Nur-Sultan | 07/16 05:00 | 25 | Shuichi Sekiguchi v Zhizhen Zhang | 7-5,6-4 | |
| Challenger Nur-Sultan | 07/15 06:45 | 24 | Shuichi Sekiguchi v Dostanbek Tashbulatov | 6-3,6-1 | |
| Challenger Fergana | 06/18 09:00 | 25 | Shuichi Sekiguchi v Marcelo Tomas Barrios Vera | Walkover | |
| Challenger Fergana | 06/17 07:25 | 24 | [412] Shuichi Sekiguchi v Makoto Ochi [374] | 6-4,6-4 | |
| ITF M25 Hong Kong | 06/09 04:00 | 29 | [359] Shintaro Imai v Shuichi Sekiguchi [423] | 6-2,6-1 | |
| ITF M25 Hong Kong | 06/08 03:00 | 28 | Yuki Mochizuki v Shuichi Sekiguchi | 3-6,6-7 | |
| ITF M25 Hong Kong | 06/07 02:00 | 27 | [423] Shuichi Sekiguchi v Yusuke Takahashi [373] | 6-3,6-3 | |
| ITF M25 Hong Kong | 06/06 02:00 | 26 | [423] Shuichi Sekiguchi v Xin Gao [390] | 6-3,6-1 | |
| ITF M25 Hong Kong | 06/04 05:25 | 25 | Shuichi Sekiguchi v Wai Yu Kai | 6-2,6-1 | |
| ITF M25 Nonthaburi | 05/31 04:40 | 27 | Rio Noguchi v Shuichi Sekiguchi | 7-5,5-7,6-1 | |
| ITF M25 Nonthaburi | 05/30 10:10 | 26 | Chayanon Kaewsuto v Shuichi Sekiguchi | 2-6,7-5,4-6 | |
| ITF M25 Nonthaburi | 05/29 06:35 | 25 | Adil Kalyanpur v Shuichi Sekiguchi | 6-7,4-6 | |
| ITF M25 Nonthaburi | 05/26 03:00 | 29 | [352] Ji Sung Nam v Shuichi Sekiguchi [422] | 1-6,4-6 | |
| ITF M25 Nonthaburi | 05/25 05:15 | 28 | [401] Harry Bourchier v Shuichi Sekiguchi [422] | 4-6,4-6 | |
| ITF M25 Nonthaburi | 05/24 04:45 | 27 | Shuichi Sekiguchi v Kelsey Stevenson | 7-6,6-2 |