Stadium: Court 3 Round: 25
| ITF Women Goyang Qual | 2018/05/08 05:05 | Yexin Ma v Ayumi Koshiishi | 4-6,3-6 |
| ITF Women Goyang Qual | 2018/05/07 03:30 | Yoo, Jin v Ayumi Koshiishi | 3-6,3-6 |
| ITF Women Gifu Qual | 2018/04/29 01:00 | Asano, Yuka v Ayumi Koshiishi | 3-6,1-6 |
| ITF Women Osaka Qual | 2018/04/07 01:30 | Ayumi Koshiishi v Akiko Omae | 3-6,2-6 |
| Kofu, Singles Qualifying W-WITF-JPN-02A | 2018/03/25 01:00 | Lykina, Ksenia v Ayumi Koshiishi | 7-5,6-7,6-3 |
| Kofu, Singles Qualifying W-WITF-JPN-02A | 2018/03/24 00:30 | Ayumi Koshiishi v Haruna Arakawa | 7-5,6-4 |
| Nishi-Tama, Singles W-WITF-JPN-01A | 2018/03/17 04:00 | Kato, Kei v Ayumi Koshiishi | 7-5,6-4 |
| ITF Women Toyota Qual | 2018/03/10 01:00 | Choi, Ji-Hee v Ayumi Koshiishi | 4-6,6-3,6-2 |
| ITF Women Goyang Qual | 2018/05/08 01:00 | Eunhye Lee v Lee, So-Ra | 4-6,2-6 |
| ITF Women Goyang Qual | 2018/05/07 02:30 | Kim, Sung Hee v Lee, So-Ra | 5-7,2-6 |
| ITF Women Gifu Qual | 2018/04/30 02:30 | Kyoka Okamura v Lee, So-Ra | 7-5,1-6,6-2 |
| ITF Women Gifu Qual | 2018/04/29 05:20 | Lee, So-Ra v Ueda, Ramu | 6-4,6-3 |
| Nishi-Tama, Singles W-WITF-JPN-01A | 2018/03/25 02:00 | Lee, So-Ra v Kim, Na Ri | 6-3,2-6,7-5 |
| Nishi-Tama, Singles W-WITF-JPN-01A | 2018/03/24 02:00 | Lee, So-Ra v Dabin Kim | 7-6,6-7,6-3 |
| Nishi-Tama, Singles W-WITF-JPN-01A | 2018/03/23 01:00 | Okuno, Ayaka v Lee, So-Ra | 3-6,4-6 |
| Nishi-Tama, Singles W-WITF-JPN-01A | 2018/03/20 06:15 | Furuya, Michiru v Lee, So-Ra | 7-5,6-7,4-6 |