| Title | Format | Country | Volumes | State |
|---|---|---|---|---|
| Octave | Manga | France | 4 | Ongoing |
| Octaveオクターヴ | Manga | Japan | 6 | Completed |
| Ogehaオゲハ | Manga | Japan | 3 | Completed |
| Ohitori-sama Shussanおひとりさま出産 | Manga | Japan | 2 | Ongoing |
| Ōkami to Kōshinryō狼と香辛料 | Manga | Japan | 16 | Completed |
| Ōkami to Kōshinryō ~Merchant meats spicy wolf.~狼と香辛料～Merchant meats spicy wolf.～ | Light novel | Japan | 24 | Ongoing |
| Old Boy | Manga | France | 4 | Completed |
| Omoide Emanonおもいでエマノン | Manga | Japan | 1 | Completed |
| Onēchan ga Kitaお姉ちゃんが来た | Manga | Japan | 14 | Ongoing |
| Onēsan wa Bushōmonoお姉さんは無精者 | Manga | Japan | 1 | Ongoing |
| Oshi no Ko | Manga | France | 8 | Ongoing |
| Otogi Matsuri | Manga | France | 12 | Completed |
| Otoyomegatari ~The Bride's Stories~乙嫁語り～The Bride's Stories～ | Manga | Japan | 13 | Ongoing |