Seiko Okamoto defeated Natsumi Hamamura 6-2 6-7 6-1 in the Ibaraki 25K round of 32 on hard. Seiko Okamoto extended the head-to-head to 2–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2007-05-28 | Gunma 25K | SF | carpet | Natsumi Hamamura | 1-6 7-6(6) 6-1 |
| 2005-02-21 | Taipei 25K | R16 | hard | Seiko Okamoto | 6-4 7-6(6) |