Stadium: Indoor C3 Round: 45
| Challenger Seoul Qual | 2018/04/30 05:00 | Renta Tokuda v Grills, Jacob | 6-3,6-2 |
| ITF Japan F4 | 2018/03/30 01:00 | Renta Tokuda v Grills, Jacob | 6-3,6-2 |
| Challenger Gimcheon Qual | 2018/05/06 07:10 | Yoshihito Nishioka v Grills, Jacob | 6-2,0-6,7-6 |
| Challenger Gimcheon Qual | 2018/05/05 05:20 | Grills, Jacob v Na, Jung-Woong | 5-7,6-4,6-3 |
| Challenger Seoul Qual | 2018/04/30 05:00 | Renta Tokuda v Grills, Jacob | 6-3,6-2 |
| Challenger Seoul Qual | 2018/04/29 04:15 | Jae Hwan Kim v Grills, Jacob | 6-4,2-6,4-6 |
| Challenger - Taipei | 2018/04/10 11:50 | Jason Jung v Grills, Jacob | 6-0,6-3 |
| Challenger Taipei Qual | 2018/04/09 03:00 | Roelofse, Ruan v Grills, Jacob | 6-4,2-6,7-6 |
| Challenger Taipei Qual | 2018/04/08 03:00 | Yu, Cheng-Yu v Grills, Jacob | 6-4,5-7,3-6 |
| Challenger Taipei Qual | 2018/04/07 02:00 | Grills, Jacob v Yunseong Chung | 6-3,2-6,6-2 |
| Challenger Gimcheon | 2018/05/11 03:15 | Renta Tokuda v Vasek Pospisil | 4-6,4-6 |
| Challenger Gimcheon | 2018/05/10 03:40 | Jason Jung v Renta Tokuda | 6-7,0-6 |
| Challenger Gimcheon | 2018/05/08 05:00 | Renta Tokuda v Wishaya Trongcharoenchaikul | 6-1,7-5 |
| Challenger Gimcheon Qual | 2018/05/07 05:00 | Renta Tokuda v Klein, Brydan | 1-6,6-3,6-4 |
| Challenger Gimcheon Qual | 2018/05/06 04:30 | Renta Tokuda v Kim, Young Seok | 6-3,6-2 |
| Challenger Seoul | 2018/05/01 06:30 | Renta Tokuda v Yang, Tsung-Hua | 1-6,2-6 |
| Challenger Seoul Qual | 2018/04/30 05:00 | Renta Tokuda v Grills, Jacob | 6-3,6-2 |
| Challenger Seoul Qual | 2018/04/29 04:55 | Renta Tokuda v Lim, Yong-Kyu | 6-4,6-4 |