Chiaki Okadaue defeated Yurina Koshino 6-3 6-2 in the Kofu 10K qualifying round on hard. The upset overturned the form book — Yurina Koshino came in leading the head-to-head 2–0, but Chiaki Okadaue had been the form player, winning 3 of their last 6 on hard. Chiaki Okadaue claimed a first win over Yurina Koshino in three meetings, narrowing the head-to-head to 2–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2015-10-19 | Hamamatsu $25K | R32 | grass | Yurina Koshino | 6-2 7-5 |
| 2014-06-09 | Kashiwa 10K | R32 | hard | Yurina Koshino | 6-7(5) 7-5 6-3 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.