Riei Kawamata defeated Seiko Okamoto 6-3 2-6 6-4 in the Kugayama 3 10K round of 16 on hard. The upset overturned the form book — Seiko Okamoto came in leading the head-to-head 1–0, defending last year's round of 16. Riei Kawamata claimed a first win over Seiko Okamoto in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1998-09-07 | Kugayama 1 10K | R16 | hard | Seiko Okamoto | 6-2 6-1 |