Stadium: Court 5 Round: 26
| ITF Korea F3 | 2018/06/18 06:30 | Lee, Tae-Woo v Kim, Young Seok | 1-6,7-6,4-6 |
| ITF Korea F2 | 2018/06/13 06:50 | Kim, Young Seok v Nam, Ji Sung | 6-7,0-6 |
| ITF Korea F1 | 2018/06/06 02:50 | Kim, Young Seok v Jae Hwan Kim | 4-6,4-6 |
| Challenger - Busan | 2018/05/15 02:00 | Kim, Young Seok v Marcos Giron | 3-6,3-6 |
| Challenger Gimcheon Qual | 2018/05/06 04:30 | Renta Tokuda v Kim, Young Seok | 6-3,6-2 |
| Challenger Gimcheon Qual | 2018/05/05 06:00 | Kim, Young Seok v Kim, Dong Ju | 6-1,6-3 |
| Challenger Seoul | 2018/05/01 04:35 | Jordan Thompson v Kim, Young Seok | 6-1,6-2 |
| ITF Thailand F12 Qual | 2017/12/10 03:00 | Kim, Young Seok v Jeong, Young-Hoon | 4-6,3-6 |
| ITF Korea F3 | 2018/06/19 08:10 | Shin, Seung-Hun v Jumpei Yamasaki | 6-4,2-6,1-6 |
| ITF Korea F2 | 2018/06/14 01:00 | Moon, Ju-Hae v Jumpei Yamasaki | 6-4,7-5 |
| ITF Korea F2 | 2018/06/12 01:00 | Lee, Tae-Woo v Jumpei Yamasaki | 3-6,0-6 |
| ITF Japan F7 | 2018/06/08 01:00 | Rio Noguchi v Jumpei Yamasaki | 6-2,6-0 |
| ITF Japan F7 | 2018/06/07 04:50 | Itsusaki, Kaito v Jumpei Yamasaki | 3-6,4-6 |
| ITF Japan F7 | 2018/06/04 03:10 | Shimizu, Kazuki v Jumpei Yamasaki | 2-6,4-6 |
| ITF China F6 | 2018/05/16 02:00 | Jumpei Yamasaki v Takeuchi, Kento (1987) | 4-6,6-4,6-7 |
| ITF China F6 | 2018/05/14 05:45 | Wang, Huixin v Jumpei Yamasaki | 3-6,3-6 |