Seiko Okamoto defeated Yurina Koshino 5-7 6-3 6-3 in the Gunma 25K round of 16 on carpet. The upset overturned the form book — Yurina Koshino came in leading the head-to-head 1–0. Seiko Okamoto claimed a first win over Yurina Koshino in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2009-03-23 | Kofu 10K | R16 | hard | Yurina Koshino | 4-6 6-4 6-3 |