Series Beginning with O
- Onna Kudoki Meshi
- Onna Matsuri Series
- Onna no ko to Misshitsu ni itara XX shichau kamoshirenai.
- Onna no Sono no Hoshi
- Onna wa sore wo yurusanai
- Onnamichi
- Onosaka, Konishi no O+K(OTASUKE)
- Onsen he Go!
- Onsen Musume
- Onsen Yosei Hakone-Chan
- Ontama!
- Ooi! Tombo
- Ookami kodomo no Ame to Yuki (Wolf Children)
- Ookami-san Series
- Ooya-san wa Shishunki !
- Opanchu Usagi
- OPERA Series
- Opus.COLORs
- orange
- Orange Page
- Ordian
- Ore Ga Sukina No Ha Imotodakedo Imoto Janai
- Ore monogatari!!
- Ore no Hanashi wa Nagai
- Ore no Imoto ga Kon nani Kawaii wake ga nai
- Ore no Kanojo to Osananajimi ga Shuraba Sugiru
- Ore no Koto Sukidesho
- Ore no nonai sentakushi ga gakuen Love comedy wo Zenryoku de Jyama Shiteiru
- Ore no Sora Series
- Ore o Suki nano wa Omae dake kayo
- Ore, Tsushima
- Ore, Twintail ni Narimasu.
- Orenchi no Furo Jijyo
- Oretachi Majikou Destroy
- Oretachi no Moe Sleeve
- Oretachin ni Tsubasa wa Nai
- Ori Sta
- Orient
- Orix Buffaloes
- Orphan Black
- Orthros no Inu
- Orustak Pictures
- Osake wa Fufu ni Nattekara
- Osama Game
- Osama Ranking
- Osananajimi ga zettai ni makenai love-come
- Osen
- Oshi ga Budokan Ittekuretara Shinu
- Oshigoto Danshi
- Oshiri Tantei
- Osomatsu-san
- Osozaki no Himawari
- Ossan's Love
- Otacool
- Otakara File
- Otaku Elf
- Otaku ni Koi wa Muzukashii
- Otenki One-san
- Otenki Sentai How Weather
- Otherside PIcnic
- Otobun
- Otoca Doll
- Otogi Jushi Akazukin
- Otoko no Kosodate
- Otoko wa Tsuraiyo
- Otokomeshi
- Otokotachi no Yamato
- Otome continue
- Otome wa Boku ni Koishiteru
- Otome Yokai Zakuro
- Otome-San
- Otona Anime
- Otona Joshi
- Otona Koukou
- otona MUSE
- Otona na Kanojo.
- Otona no Boguya-san
- Otona no Kagaku Magazine
- Otona no Natsuyasumi
- Otona No Nurie
- Otona no Oshare Techo
- Otosan to Yobasete
- Otoyome Gatari
- Ougon no Buta
- Ougon no Gt
- Our Dearest Sakura (Doki no Sakura)
- OUR HOUSE
- Ouran Koko Host Club
- Ouroboros
- Outbreak Company
- Outlandar
- Over 30
- Over Drive
- Overlord
- Overman King-Gainer
- Overtake!
- Owarai Danshiko
- Oyasumi Punpun
- Oyuki Umi no Kina
- OZMAFIA!!