| ITF - W100 Tokyo | 04/22 03:15 | 54 | [457] Erika Sema v Natsumi Kawaguchi [393] | 6-4,7-6 | |
| ITF - W35 Osaka | 04/09 01:00 | 25 | [392] Natsumi Kawaguchi v Sara Saito [236] | 4-6,1-6 | |
| ITF - W50 Kashiwa | 04/01 05:55 | 45 | [374] Natsumi Kawaguchi v Miho Kuramochi [392] | 2-6,3-6 | |
| ITF - W50 Kofu | 03/27 00:30 | 54 | Natsumi Kawaguchi v Ikumi Yamazaki | 4-6,6-2,2-6 | |
| ITF - W15 Hinode | 03/21 01:00 | 26 | Kayo Nishimura v Natsumi Kawaguchi | 2-6,6-2,6-0 | |
| ITF - W15 Hinode | 03/19 01:00 | 25 | Mio Mushika v Natsumi Kawaguchi | 4-6,7-6,4-6 | |
| ITF W40 Yokohama | 11/30 01:00 | 26 | [365] Natsumi Kawaguchi v Mai Hontama [117] | 4-6,3-6 | |
| ITF W40 Yokohama | 11/29 02:45 | 25 | [365] Natsumi Kawaguchi v En Shuo Liang [258] | 7-6,6-4 | |
| ITF W100 Takasaki | 11/20 02:30 | 54 | [128] Luksika Kumkhum v Natsumi Kawaguchi [352] | 6-3,4-6,7-5 | |
| ITF W100 Takasaki | 11/13 07:25 | 54 | [269] Sijia Wei v Natsumi Kawaguchi [352] | 7-5,6-0 | |
| ITF W100 Takasaki | 11/13 04:30 | 54 | Rinon Okuwaki v Natsumi Kawaguchi | 4-6,2-6 | |
| ITF W60 Sydney | 10/30 23:00 | 25 | [381] Yuki Naito v Natsumi Kawaguchi [349] | 7-5,7-5 | |
| ITF W60 Playford | 10/25 01:10 | 25 | [357] Natsumi Kawaguchi v Jaimee Fourlis [212] | 6-3,5-7,1-6 | |
| ITF W25 Hamamatsu | 10/12 02:45 | 26 | [346] Natsumi Kawaguchi v Saki Imamura [273] | 1-6,2-6 | |
| ITF W25 Hamamatsu | 10/10 03:40 | 25 | Natsumi Kawaguchi v Nana Kawagishi | 6-3,5-7,6-2 | |
| WTA Tokyo | 09/26 04:50 | 25 | Natsumi Kawaguchi v Despina Papamichail | Cancelled | |
| WTA Tokyo | 09/24 02:35 | 19 | [177] Himeno Sakatsume v Natsumi Kawaguchi [387] | 6-7,4-6 | |
| WTA Tokyo | 09/23 05:25 | 14 | [86] Schoofs, Bibiane v Natsumi Kawaguchi [387] | 4-6,3-6 | |
| Kyoto, Qualifications Simples W-ITF-JPN-15A | 09/20 00:50 | 25 | Natsumi Kawaguchi v Akiko Omae | 1-6,6-4,1-6 | |
| Osaka, Japon | 09/09 06:55 | 14 | [199] Himeno Sakatsume v Natsumi Kawaguchi [386] | 6-3,6-3 | |
| ITF - W100 Tokyo | 09/05 02:00 | 25 | [195] Alexandra Eala v Natsumi Kawaguchi [386] | 6-4,6-3 | |
| ITF W40 Hong Kong | 08/22 02:00 | 25 | [241] Anastasia Zakharova v Natsumi Kawaguchi [387] | 6-4,6-2 | |
| ITF W40 Hong Kong | 07/04 04:25 | 25 | [447] Ayano Shimizu v Natsumi Kawaguchi [380] | 6-4,7-5 | |
| Hong Kong, Simples W-ITF-HKG-01B | 06/29 03:20 | 26 | [414] Ya Yi Yang v Natsumi Kawaguchi [375] | 6-3,6-1 | |
| Hong Kong, Simples W-ITF-HKG-01B | 06/27 04:45 | 25 | Monique Barry v Natsumi Kawaguchi | 2-6,1-6 | |
| ITF W25 Tokyo | 06/01 00:50 | 26 | [394] Natsumi Kawaguchi v Aoi Ito [393] | 0-6,3-6 | |
| ITF W25 Tokyo | 05/31 02:55 | 25 | Natsumi Kawaguchi v Nana Kawagishi | 6-3,6-2 | |
| Karuizawa, Singles W-ITF-JPN-12A | 05/26 02:10 | 26 | [385] Natsumi Kawaguchi v Johanne C Svendsen [429] | 6-4,3-6,1-6 | |
| Karuizawa, Singles W-ITF-JPN-12A | 05/24 04:35 | 25 | Rinon Okuwaki v Natsumi Kawaguchi | 0-6,4-6 | |
| Kurume, Singles W-ITF-JPN-11A | 05/17 01:00 | 25 | Natsumi Kawaguchi v Eri Shimizu | 3-6,4-6 |