Series Beginning with O
- Overlord
- Overman King-Gainer
- Overtake!
- Owarai Danshiko
- Oyasumi Punpun
- Oyuki Umi no Kina
- OZMAFIA!!
- Ozuma
- Please Tell Me! Galko-chan
- Scenes from Awajima (Awajishima Hyakkei)
- Seraph of the End
- Shomin Sample
- The Oblivious Saint Can't Contain Her Power (Mujikaku Seijo wa Kyomo Muishiki ni Chikara wo Tarenagasu)
- The Ogre's Bride
- The Other World's Books Depend on the Bean Counter
- The Royal Tutor (Oshitsu Kyoshi Haine)
- Uncle from Another World