Our Last Crusade or the Rise of a New World
OniAi
Origin: Spirits of the Past
Oretachi ni Tsubasa wa Nai: Hadairo Ritsu Kyuuwari Zou!?
Onmyoji
Ore no Imouto ga Konnani Kawaii Wake ga Nai.
ORESUKI Are you the only one who loves me? - Our Playball / Our End Run / Our Game
Ouran High School Host Club
Overtake!
Oreshura
Ore no Imouto ga Konnani Kawaii Wake ga Nai.: Ore no Imouto ga Konnani Eroge na Wake Nai
Otome wa Boku ni Koishiteru: Futari no Elder The Animation