Groups
- nurunuru x 3
- nwa garupan san team 3
- nxt-club 3
- nyanpunibocchi 3
- nyao spirits 3
- nyoropedia 3
- o-chu-gen 3
- oboro mitsurin dan 3
- oburigakko 3
- oc5 3
- ochi mono kanzume 3
- octo 3
- offt. 3
- og 3
- ogimachi 3
- ohayo yozy 3
- ohka works 3
- oikaze 3
- oji-san no saifu 3
- okaya 3
- okayu kyoushitsu 3
- okhotsk-kai 3
- okujou no chikashitsu 3
- okuribidokei 3
- omaera no ai de jisuu seigen koeta 3
- omega 3
- omega sol 3
- omochi fry-ya-san 3
- omochop 3
- omokaji ippai ippai 3
- omomuki high jump 3
- omu omurice 3
- omurice teishoku 3
- on my way 3
- onbre garden 3
- onda akemi 3
- one night dream 3
- one night stand 3
- one side factory 3
- onelookers 3
- onibi kuudan 3
- onikibitou 3
- onion software 3
- oobae toudai 3
- ooinu no fuguri 3
- ookami koubou 3
- oomune soft 3
- oosaka gundan 3
- ootaichi 3
- oppai empire 3