- Okugawa-iine
- Okugawa-kayane
- Okugawa-toyoshima
- Ōkura
- Ōmata
- Ōmatsukawa
- Ōmika
- Ōmomo
- Omotegō-banzawa
- Omotegō-fukaado
- Omotegō-kaneyama
- Onahama
- Ononiimachi
- Onoda
- Onogawa
- Onogawa
- Oragahama
- Orikuchihara
- Ōsemachi-kōzu
- Ōsemachi-tadano
- Ōshio
- Oshizawa
- Ōta
- Ōtaira
- Ōtani
- Ōtera
- Otokane
- Ōtomachi-amaya
- Ōtomachi-ashinomaki
- Ōtomachi-kamimiyori