| ITF W100 Gifu | 04/30 07:05 | 25 | [282] Aoi Ito v Sayaka Ishii [326] | Retired | |
| ITF W100 Tokyo | 04/24 08:00 | 25 | [326] Sayaka Ishii v Eudice Chong [314] | 6-3,3-6,6-7 | |
| ITF W35 Osaka | 04/14 02:00 | 29 | [265] Stacey Fung v Sayaka Ishii [371] | 1-6,6-3,3-6 | |
| ITF W35 Osaka | 04/13 02:45 | 28 | [371] Sayaka Ishii v Mananchaya Sawangkaew [227] | 7-5,7-5 | |
| ITF W35 Osaka | 04/12 01:00 | 27 | [371] Sayaka Ishii v Ya-Hsuan Lee [320] | 6-4,6-2 | |
| ITF W35 Osaka | 04/11 03:15 | 26 | [262] Maddison Inglis v Sayaka Ishii [371] | 7-6,4-6,4-6 | |
| ITF W35 Osaka | 04/10 00:55 | 25 | Sayaka Ishii v Lea Ma | Retired | |
| ITF W50 Kashiwa | 04/05 05:30 | 27 | [142] Arianne Hartono v Sayaka Ishii [381] | 5-7,6-2,6-4 | |
| ITF W50 Kashiwa | 04/04 01:35 | 26 | [354] Naho Sato v Sayaka Ishii [381] | 4-6,3-6 | |
| ITF W50 Kashiwa | 04/03 07:10 | 25 | [381] Sayaka Ishii v Talia Gibson [184] | 7-6,2-6,6-4 | |
| ITF W50 Kashiwa | 04/01 01:00 | 45 | [278] Lanlana Tararudee v Sayaka Ishii [381] | Retired | |
| ITF W50 Kashiwa | 03/31 01:00 | 45 | Moeka Miyata v Sayaka Ishii | 1-6,2-6 | |
| WTA Miami | 03/17 15:00 | 14 | [78] Bernarda Pera v Sayaka Ishii [373] | 6-0,6-4 | |
| ITF W35 Traralgon | 02/28 01:55 | 25 | [354] Jia-Jing Lu v Sayaka Ishii [386] | 6-2,6-4 | |
| ITF W35 Traralgon | 02/23 00:00 | 27 | [385] Sayaka Ishii v Naho Sato [396] | 4-6,1-6 | |
| ITF W35 Traralgon | 02/22 00:45 | 26 | [385] Sayaka Ishii v Naiktha Bains [452] | 6-3,6-2 | |
| ITF W35 Traralgon | 02/21 04:45 | 25 | [208] Sijia Wei v Sayaka Ishii [385] | 2-6,6-7 | |
| ITF W35 Wesley Chapel | 02/08 15:40 | 26 | Sayaka Ishii v Panna Bartha | 6-1,6-7,2-6 | |
| ITF W35 Wesley Chapel | 02/06 17:25 | 25 | [385] Sayaka Ishii v Maria Kozyreva [422] | 6-4,6-2 | |
| ITF W75 Vero Beach | 01/25 16:00 | 26 | [490] Clervie Ngounoue v Sayaka Ishii [411] | 6-4,6-3 | |
| ITF W75 Vero Beach | 01/24 16:00 | 25 | Fernanda C Huerta v Sayaka Ishii | 1-6,0-6 | |
| ITF W75 Vero Beach | 01/23 16:00 | 54 | [411] Sayaka Ishii v Anna Rogers [193] | 6-2,6-7,6-3 | |
| ITF W75 Vero Beach | 01/22 20:35 | 54 | Sayaka Ishii v Mia Yamakita | 6-2,7-5 | |
| ITF W50 Nonthaburi | 01/13 02:55 | 28 | [451] Sayaka Ishii v Mananchaya Sawangkaew [266] | 6-3,2-6,5-7 | |
| ITF W50 Nonthaburi | 01/12 03:00 | 27 | [242] Dalila Jakupovic v Sayaka Ishii [451] | 0-6,0-6 | |
| ITF W50 Nonthaburi | 01/11 03:00 | 26 | [451] Sayaka Ishii v Ksenia Zaytseva [366] | 6-2,6-4 | |
| ITF W50 Nonthaburi | 01/10 04:20 | 25 | [364] Punnin Kovapitukted v Sayaka Ishii [451] | 6-4,1-6,0-6 | |
| ITF W50 Nonthaburi | 01/08 04:25 | 54 | [445] Evgeniya Rodina v Sayaka Ishii [451] | 3-6,4-6 | |
| ITF W50 Nonthaburi Qual | 01/07 07:35 | 54 | Watsachol Sawatdee v Sayaka Ishii | 2-6,1-6 | |
| ITF W50 Nonthaburi | 01/05 04:35 | 27 | [474] Sayaka Ishii v Antonia Ruzic [244] | 3-6,2-6 |