Game Music Series Beginning with O
- [Oshi no ko]
- Obey Me!
- Occultic;Nine
- Octave
- OCTOPATH TRAVELER
- Oda Nobuna no Yabou
- Ojisama Senka
- One Piece
- One Room
- Ongaku Shojo
- ONGEKI
- Onigiri
- Onimai: I'm Now Your Sister!
- Online Game
- Onsen Musume
- Opus.COLORs
- Oretachi Majikou Destroy
- Oretachin ni Tsubasa wa Nai
- Otoca Doll
- Otome wa Boku ni Koishiteru
- Outbreak Company
- The Royal Tutor (Oshitsu Kyoshi Haine)