Art & Entertainment Series Beginning with O
- [Oshi no ko]
- Curious George
- Obey Me!
- Ochoyan
- Octave
- Oda Nobuna no Yabou
- Odoru Daisosasen Series
- Oh-oku ( Danjo Gyakuten)
- Ohisama
- Oi! Hanimaru
- Ojamajo
- Ojarumaru
- Ojiisan Sensei
- Oka-san Musume wo Yameteiidesuka?
- Okaeri Mone
- Okami Shojo to Kuro Oji
- Okasan to Issho
- Okusama wa Toriatsukaichui
- Olympic
- Omae Umasodana
- Omoi, Omoware, Furi, Furare
- Omoide no Marnie (When Marnie Was There)
- Omotesandou Kouko Gassyobu!
- Omukaedesu.
- Once Upon a Time in High School
- One Piece
- Onegai My Melody
- Ongaku to Hito
- Ongaku-shi ga Kakanai Jpop Hihyo
- Onihei Hankacho
- Online Game
- Only Yesterday
- Onna Joshu Naotora
- Ookami kodomo no Ame to Yuki (Wolf Children)
- Ookami-san Series
- orange
- Ore no Koto Sukidesho
- Ori Sta
- Orix Buffaloes
- Orthros no Inu
- Osama Ranking
- Oshigoto Danshi
- Oshiri Tantei
- Osomatsu-san
- Osozaki no Himawari
- Ossan's Love
- Otacool
- Otakara File
- Otaku ni Koi wa Muzukashii
- Otenki One-san
- Otoko wa Tsuraiyo
- Otokotachi no Yamato
- Otome continue
- Otona Anime
- Otona Joshi
- Otona no Kagaku Magazine
- Otona no Natsuyasumi
- Otona No Nurie
- Ougon no Gt
- Our Dearest Sakura (Doki no Sakura)
- Ouran Koko Host Club
- Outlandar
- Overlord
- Owarai Danshiko
- Seraph of the End