Maya Kato defeated Ayumi Oka 6-2 6-2 in the Noto 25K round of 16 on carpet. The upset overturned the form book — Ayumi Oka came in leading the head-to-head 3–2. Maya Kato narrowed the head-to-head to 3–3.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2009-06-08 | Tokyo 10K | R32 | hard | Ayumi Oka | 7-6(4) 6-0 |
| 2006-09-11 | Hiroshima 10K | R32 | carpet | Ayumi Oka | 5-7 6-3 6-0 |
| 2006-09-04 | Kyoto 10K | R32 | carpet | Ayumi Oka | 6-0 6-4 |
| 2005-06-06 | Tokyo 1 10K | R32 | hard | Maya Kato | 7-6(5) 6-3 |
| 2004-09-20 | Hiroshima 10K | R32 | grass | Maya Kato | 7-5 6-2 |