Series Beginning with O
- [Oshi no ko]
- Curious George
- My Next Life as a Villainess: All Routes Lead to Doom!
- Obey Me!
- Occultic;Nine
- Oceanic Moon
- Ochikobore Fruits Tarte
- Ochoyan
- Octave
- OCTOPATH TRAVELER
- Oda Nobuna no Yabou
- Oda Shinamon Nobunaga
- Odd Taxi
- Odekake Kozame
- Odoru Daisosasen Series
- Oedo Rocket
- Oh! Mickey
- Oh! My Girl!!
- Oh! Super MILK Chan
- Oh, My Dad!!
- Oh-oku ( Danjo Gyakuten)
- Oh-oku / Ooku
- Ohisama
- Ohitori sama
- Ohoka Echizen
- Oi! Hanimaru
- Oishi Propose
- Oishii Coffee no Irekata
- Oishii Gohan
- Oishinbo
- Ojamajo
- Ojarumaru
- Oji No Hommei Ha Akuyaku Reijo
- Ojiisan Sensei
- Ojisama (warai) Series
- Ojisama Senka
- Ojisan Ha Kawai I Mono Ga Osuki.
- Ojisan to Marshmallow
- Oka-san Musume wo Yameteiidesuka?
- Okaeri Mone
- Okami Kakushi
- Okami San Ha Taberaretai
- Okami San Ha Taberaretai
- Okami Shojo to Kuro Oji
- Okami to Koshinryo (Wolf and Spice)
- Okane ga Nai!
- Okasan to Issho
- Okiku Furikabutte
- Okitegami Kyoko Series
- Okoshiyasu Chitose Chan
- Okusama ga Seito Kaicho!
- Okusama wa Maho Shojo
- Okusama wa Toriatsukaichui
- Ol Nippon
- Olympia Cuculus
- Olympic
- Omae Umasodana
- Omae wa mada Gunma wo shiranai
- Omamori Himari
- OMISHI MAGICAL THEATER: RISKY & SAFETY
- Omiyasan
- OmniSheep
- Omo ni Naiteimasu
- Omoi, Omoware, Furi, Furare
- Omoide no Marnie (When Marnie Was There)
- Omoshiro Nankyoku Ryorinin
- Omotesandou Kouko Gassyobu!
- Omukaedesu.
- On Air Dekinai!
- on BLUE Series
- Onago Series
- Once Upon a Time in High School
- ONE - Kagayaku Kisetsu e
- One Off
- One Piece
- One Punch Man
- One Room
- Oneechan ga Kita
- Onegai My Melody
- Onegai Teacher (Please Teacher!)
- Onegai Twins
- Ongaku Shojo
- Ongaku to Hito
- Ongaku-shi ga Kakanai Jpop Hihyo
- ONGEKI
- Oni-Chan no Koto Nanka Zenzen Sukijanaindakarane!!
- Onichan Dakedo Ai Sae Areba Kankeinaiyone
- Onigamiden
- Onigiri
- Onihei Hankacho
- Onimai: I'm Now Your Sister!
- Onimusha
- Onipan!
- Oniyome Nikki
- Onkyokaiwa
- Online Game
- Only Mercedes
- Only Yesterday
- Onna Joshu Naotora
- Onna Keiji Mizuki