Stadium: Court A7 Round: 25 Ground: Synthetic outdoor
| Tsukuba, Singles W-WITF-JPN-09A | 2018/08/22 00:30 | Shiho Akita v Ushijima, Risa | 2-6,2-6 |
| Nonthaburi, Simples W-WITF-THA-09A | 2018/08/13 02:00 | Michika Ozeki v Shiho Akita | 6-1,6-2 |
| Nonthaburi, Simples W-WITF-THA-09A | 2018/08/06 02:30 | Shiho Akita v Rutuja Bhosale | 6-4,1-6,6-2 |
| ITF Women Granby | 2018/07/24 22:25 | Astra Sharma v Shiho Akita | 7-6,6-1 |
| ITF Women Gatineau | 2018/07/16 14:00 | Sophie Chang v Shiho Akita | 6-4,5-7,6-1 |
| ITF Women Honolulu | 2018/07/10 23:20 | Usue Maitane Arconada v Shiho Akita | 6-0,1-6,7-6 |
| ITF Women Daegu | 2018/06/20 01:00 | Shiho Akita v Hanna Chang | 0-6,5-7 |
| Karuizawa, Singles W-WITF-JPN-10A | 2018/05/22 01:00 | Chihiro Muramatsu v Shiho Akita | 6-2,6-4 |
| Tsukuba, Singles W-WITF-JPN-09A | 2018/08/21 00:30 | Sawayanagi, Riko v Momoko Kobori | 4-6,3-6 |
| ITF Women Toyota Qual | 2018/03/11 03:30 | Sawayanagi, Riko v Iwai, Mayu | 6-0,1-6,2-6 |
| ITF Women Toyota Qual | 2018/03/10 01:00 | Sawayanagi, Riko v Himari Sato | 7-5,6-0 |
| Mildura, Simples W-WITF-AUS-04A | 2018/03/06 01:05 | Maddison Inglis v Sawayanagi, Riko | 6-0,6-2 |
| ITF Women Perth Qual | 2018/02/19 05:05 | Sawayanagi, Riko v Lulu Sun | 2-6,3-6 |
| ITF Women Perth Qual | 2018/02/18 03:00 | Sawayanagi, Riko v Ueda, Ramu | 6-3,7-5 |
| Perth, Simples W-WITF-AUS-05A | 2018/02/15 02:00 | Sawayanagi, Riko v Minokoshi, Mai | 1-6,1-6 |
| ITF Women Perth Qual | 2018/02/12 04:35 | Sawayanagi, Riko v Chernyshova, Maryna | 6-4,6-2 |