Anime CD Series Beginning with O
- [Oshi no ko]
- My Next Life as a Villainess: All Routes Lead to Doom!
- Obey Me!
- Occultic;Nine
- Ochikobore Fruits Tarte
- Octave
- Oda Nobuna no Yabou
- Oda Shinamon Nobunaga
- Odd Taxi
- Oishinbo
- Ojamajo
- Ojisama Senka
- Ojisan Ha Kawai I Mono Ga Osuki.
- Ojisan to Marshmallow
- Okami Shojo to Kuro Oji
- Okami to Koshinryo (Wolf and Spice)
- Okitegami Kyoko Series
- Okoshiyasu Chitose Chan
- Okusama ga Seito Kaicho!
- Omae wa mada Gunma wo shiranai
- Omoi, Omoware, Furi, Furare
- Omoide no Marnie (When Marnie Was There)
- One Off
- One Piece
- One Punch Man
- One Room
- Ongaku Shojo
- ONGEKI
- Onichan Dakedo Ai Sae Areba Kankeinaiyone
- Onigiri
- Onimai: I'm Now Your Sister!
- Onipan!
- Online Game
- Onsen Musume
- Onsen Yosei Hakone-Chan
- Opus.COLORs
- orange
- Ore Ga Sukina No Ha Imotodakedo Imoto Janai
- Ore monogatari!!
- Ore no Imoto ga Kon nani Kawaii wake ga nai
- Ore no Kanojo to Osananajimi ga Shuraba Sugiru
- Ore no nonai sentakushi ga gakuen Love comedy wo Zenryoku de Jyama Shiteiru
- Ore o Suki nano wa Omae dake kayo
- Ore, Twintail ni Narimasu.
- Orenchi no Furo Jijyo
- Oretachi Majikou Destroy
- Oretachin ni Tsubasa wa Nai
- Orient
- Osake wa Fufu ni Nattekara
- Osama Game
- Osama Ranking
- Osananajimi ga zettai ni makenai love-come
- Oshi ga Budokan Ittekuretara Shinu
- Oshiri Tantei
- Osomatsu-san
- Ossan's Love
- Otaku Elf
- Otaku ni Koi wa Muzukashii
- Otherside PIcnic
- Outbreak Company
- Overlord
- Overtake!
- Oyuki Umi no Kina
- Ozuma
- Please Tell Me! Galko-chan
- Seraph of the End
- Shomin Sample
- The Royal Tutor (Oshitsu Kyoshi Haine)
- Uncle from Another World