2018 Japan Women's Open – Singles

Zarina Diyas was the defending champion, but lost in the quarterfinals to Zhang Shuai.

Hsieh Su-wei won her first title in six years, beating Amanda Anisimova in the final 6–2, 6–2.

Seeds
• # 🇨🇳 Zhang Shuai (semifinals)

• # Hsieh Su-wei (champion)

• # 🇰🇿 Yulia Putintseva (first round, retired)

• # 🇨🇳 Wang Qiang (semifinals)

• # 🇦🇺 Ajla Tomljanović (quarterfinals)

• # 🇰🇿 Zarina Diyas (quarterfinals)

• # 🇨🇳 Zheng Saisai (second round)

• # 🇵🇱 Magda Linette (quarterfinals)

Seeds
• #🇺🇸 Amanda Anisimova (qualified)

• #🇩🇪 Antonia Lottner (first round)

• #🇦🇺 Arina Rodionova (qualified)

• #🇨🇳 Han Xinyun (second round)

• #🇬🇧 Harriet Dart (second round)

• #🇲🇪 Danka Kovinić (first round)

• #🇦🇺 Priscilla Hon (qualified)

• #🇰🇷 Jang Su-jeong (qualifying competition)

Qualifiers
• #🇺🇸 Amanda Anisimova

• #🇨🇳 Zhang Yuxuan

• #🇦🇺 Arina Rodionova

• #🇦🇺 Priscilla Hon