Natsumi Hamamura defeated Ayumi Oka 7-6 7-6 in the Nagano 25K qualifying round on carpet. The result followed the form book — Natsumi Hamamura came in leading the head-to-head 2–1. Natsumi Hamamura extended the head-to-head to 3–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2008-10-20 | Hamanako 25K | R32 | carpet | Natsumi Hamamura | 6-2 6-4 |
| 2006-09-11 | Hiroshima 10K | QF | carpet | Natsumi Hamamura | 6-2 6-3 |
| 2005-10-17 | Makinohara 25K | R32 | carpet | Ayumi Oka | 7-6(3) 4-6 6-3 |