Music Series Beginning with O
- [Oshi no ko]
- Curious George
- Odoru Daisosasen Series
- Ohoka Echizen
- Ojamajo
- Okami to Koshinryo (Wolf and Spice)
- Okasan to Issho
- Okitegami Kyoko Series
- Omoi, Omoware, Furi, Furare
- Omoide no Marnie (When Marnie Was There)
- One Piece
- Onegai My Melody
- Onimai: I'm Now Your Sister!
- Online Game
- Only Yesterday
- Ookami kodomo no Ame to Yuki (Wolf Children)
- Ore no Imoto ga Kon nani Kawaii wake ga nai
- Orix Buffaloes
- Osen
- Osomatsu-san
- Ossan's Love
- Otoca Doll
- Ouran Koko Host Club
- Overlord
- Seraph of the End
- The Royal Tutor (Oshitsu Kyoshi Haine)