Misaki Doi has not reached a WTA quarterfinal since Nurnberg 2017, although the Japanese No.2 did lift the trophy at the Bastad 125K this July. The former World No.30's best Japan Women's Open showings to date are a semifinal in 2012 and a quarterfinal in 2013 - the latter being the most recent occasion the tournament had two home players in the last eight.
Qualifier Zoe Hives' upset of No.4 seed Anastasia Potapova means that the Australian has won her first-round match in all three WTA main draws she has contested. The 22-year-old is now bidding to make her quarterfinal debut.
Mihaela Buzarnescu is seeking to make her first quarterfinal since lifting her maiden trophy in San Jose last August. The Romanian suffered an ankle injury in Montréal the following week, and has compiled just an 11-29 win-loss record since returning to action, with her ranking slipping from a high of World No.20 to its current World No.125.
Wildcard Kurumi Nara is bidding to make her first WTA quarterfinal since Tashkent 2017. After that tournament, the former World No.32 went on a 16-match losing streak in WTA main draws, only snapped at Roland Garros this May. Nara's best performances at the Japan Women's Open were a semifinal run in 2013 and a quarterfinal in 2016.
No.3 seed Alison Van Uytvanck clashes with her doubles partner this week and occasional coach Kirsten Flipkens in an all-Belgian derby. The compatriots are all square at 2-2, with Van Uytvanck winning 6-2, 6-4 in both the 2015 Katowice quarterfinals and the 2019 St Petersburg first round, and Flipkens taking their 2016 Monterrey second round 6-2, 4-6, 6-3 (their only previous outdoor hardcourt encounter) and their 2018 Nurnberg first round 7-6(5), 2-6, 7-6(2). Indeed, those two wins are Flipkens' only victories over fellow Belgians at Tour main draw level in 11 matches; Van Uytvanck's equivalent record is 3-4.
No.7 seed Sara Sorribes Tormo faces Varvara Flink for the second time this year, having defeated the Russian 6-3, 6-2 in the second round of the Bol 125K in June. Flink is bidding to reach her maiden WTA-level quarterfinal.
ORDER OF PLAY (all courts start 11.30am)
Mihaela BUZARNESCU (ROU) vs [WC] Kurumi NARA (JPN)
 Alison VAN UYTVANCK (BEL) vs Kirsten FLIPKENS (BEL)
Misaki DOI (JPN) vs [Q] Zoe HIVES (AUS)
 Eri HOZUMI (JPN) / Makoto NINOMIYA (JPN) vs Christina MCHALE (USA) / Valeria SAVINYKH (RUS)
 Sara SORRIBES TORMO (ESP) vs Varvara FLINK (RUS)
Not before 1pm
Anastasia POTAPOVA (RUS) / Yana SIZIKOVA (RUS) vs Haruka KAJI (JPN) / Junri NAMIGATA (JPN)
Hayley CARTER (USA) / Ena SHIBAHARA (JPN) vs Miyu KATO (JPN) / Storm SANDERS (AUS)