All cities

• Ōmagari
• Ōmamachō-ōmama
• Ōme
• Ōmihachiman
• Ōmiya
• Ōmura
• Ōmuta
• Ōno-hara
• Ōnojō
• Ōsaki
• Ōsaki
• Ōta
• Ōtake
• Ōtaki
• Ōtawara
• Ōtsu
• Ōtsuchi
• Ōtsuki
• Ōwani
• Ōyama