Otome Series
- ALL OUT!!
- Obey Me!
- Occultic;Nine
- OCTOPATH TRAVELER
- Opus.COLORs
- orange
- Otome continue
- Over Drive
- OZMAFIA!!
- [Oshi no ko]
- Oishi Propose
- Okiku Furikabutte
- Okasan to Issho
- Okusama ga Seito Kaicho!
- Okoshiyasu Chitose Chan
- Please Tell Me! Galko-chan
- Oshiri Tantei
- Ojarumaru
- Osomatsu-san
- Ossan's Love
- Otogi Jushi Akazukin
- Otome Yokai Zakuro
- Onegai Twins
- Onegai Teacher (Please Teacher!)
- Onegai My Melody
- Omae Umasodana
- Omamori Himari
- Ojamajo
- Oshigoto Danshi
- Onichan Dakedo Ai Sae Areba Kankeinaiyone
- Otenki Sentai How Weather
- A Girl & Her Guard Dog
- Omukaedesu.
- Okane ga Nai!
- Ookami-san Series
- Okami Shojo to Kuro Oji
- Octave
- Ojisama Senka
- Ozuma
- The Diary of Ochibi-san
- Odd Taxi
- Otona Anime
- Orient
- Olympic
- Alternative Girls
- Orenchi no Furo Jijyo
- Online Game
- Overman King-Gainer
- Overlord
- My Next Life as a Villainess: All Routes Lead to Doom!
- Trapped in a Dating Sim: The World of Otome Games is Tough for Mobs
- Otobun
- Oretachin ni Tsubasa wa Nai
- Oretachi Majikou Destroy
- Ore no Imoto ga Kon nani Kawaii wake ga nai
- Ore no Kanojo to Osananajimi ga Shuraba Sugiru
- Ore o Suki nano wa Omae dake kayo
- Ore monogatari!!
- Oh-oku ( Danjo Gyakuten)
- Ooya-san wa Shishunki !
- Oedo Rocket
- Tenkuu Shinpan
- Okusama wa Maho Shojo
- Onna no Sono no Hoshi
- Onosaka, Konishi no O+K(OTASUKE)
- Osananajimi ga zettai ni makenai love-come
- Omoi, Omoware, Furi, Furare
- Omoide no Marnie (When Marnie Was There)
- Oshi ga Budokan Ittekuretara Shinu
- Gekkan Otokomae Zukan
- Ouran Koko Host Club
- Okami to Koshinryo (Wolf and Spice)
- KING OF BANDIT JING
- Ojisama (warai) Series
- The Royal Tutor (Oshitsu Kyoshi Haine)
- Osama Game
- Osama Ranking
- Seraph of the End
- Oda Shinamon Nobunaga
- Oda Nobuna no Yabou
- Oishinbo
- Onkyokaiwa
- Ongaku to Hito
- Onihei Hankacho
- Onigiri
- Onimusha
- Onigamiden