Light Novel Series
- Occultic;Nine
- OCTOPATH TRAVELER
- OZMAFIA!!
- [Oshi no ko]
- Oishii Coffee no Irekata
- Okami Kakushi
- Ookami kodomo no Ame to Yuki (Wolf Children)
- Treat of Reincarnation
- Osomatsu-san
- Otogi Jushi Akazukin
- Onegai Twins
- Onegai Teacher (Please Teacher!)
- Onegai My Melody
- Omamori Himari
- Ontama!
- Ojamajo
- Onichan Dakedo Ai Sae Areba Kankeinaiyone
- Okane ga Nai!
- The Angel Next Door Spoils Me Rotten
- Ookami-san Series
- Okami Shojo to Kuro Oji
- Hortensia Saga
- Online Game
- Overlord
- Otome wa Boku ni Koishiteru
- 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
- Ore, Twintail ni Narimasu.
- Shomin Sample
- Ore Ga Sukina No Ha Imotodakedo Imoto Janai
- Special training in the Secret Dungeon
- Ore no Imoto ga Kon nani Kawaii wake ga nai
- Ore no Kanojo to Osananajimi ga Shuraba Sugiru
- Ore no nonai sentakushi ga gakuen Love comedy wo Zenryoku de Jyama Shiteiru
- Ore o Suki nano wa Omae dake kayo
- Ore monogatari!!
- Osananajimi ga zettai ni makenai love-come
- Okitegami Kyoko Series
- Okami to Koshinryo (Wolf and Spice)
- Seraph of the End
- Oda Nobuna no Yabou
- Oniyome Nikki
- Onimusha