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| Okasare Miki-chan to Hentai Oji-san | 2011-01-24 | 5.40 (22) |
| Okasare Yuusha II ~Yuusha na no ni, Chinchin o Pikupiku Sarete Bakari no Boku...~ | 2012-08-24 | 6.70 (488) |
| Okasare Yuusha III ~Yuusha na no ni, Binkan Sugiru Boku no Ochinchin...~ | 2013-07-19 | 6.40 (342) |
| Okasare Yuusha IV ~ANOTHER STORY~ | 2014-04-25 | 6.20 (40) |
| Okasare Yuusha IV ~Mou Dame. Boku no Ochinchin wa Genkai na no ni~ | 2013-12-31 | 6.80 (98) |
| Okasare Yuusha V ~ Donna ni Level o Agete mo, Sugu Shasei Shichau Boku no Ochinchin...~ | 2014-07-25 | 7.10 (86) |
| Okasare Yuusha ~Ririshiku Sekai o Sukuu Hazu Datta Boku...~ | 2011-12-16 | 5.70 (696) |
| Okashi na Shima no Peter Pan ~Sweet Never Land~ | 2011-10-06 | 6.60 (25) |
| Okashi no Kuni no Gâteau Sorcière | 2023-09-16 | - |
| Okashina Kuni no Sweet Festival! | 2011-08-27 | - |
| Okashina Monogatari | 2025-10-10 | 7.20 (23) |
| Okashina o Hisama | 2009-03-20 | - |
| Okashiya-san ni Nerawareta! | 2015-07-15 | 7.00 (21) |
| Okatai Ojou-sama Kyoushi wa Kyonyuu Tsuma ~Fuufu no Akashi ni Anata no Seishi de Haramasenasai~ | 2008-12-31 | 6.40 (14) |
| Okayu Nyumu! | 2025-02-27 | 6.90 (26) |
| Okiba ga Nai! | 2010-05-27 | 7.20 (51) |
| Okiku's Well | - | - |
| Okinawa Slave Island | 2010-02-27 | 4.60 (40) |
| Okinawa Toaru Saikyou Densetsu | 2016-06-01 | - |
| Okini Mesumama... | 2008-11 | - |
| Okinimesu Mama | 2016-12-22 | - |
| Okite no Mura | 2005-02-03 | - |
| Okite no Shima | 2003-01-24 | - (4) |
| Okite ~ Joshi Basuke-bu no Himitsu ~ | 2008-07-03 | - (1) |
| Okitsune Nakadashi Ongaeshi ~Onee-san no Naka de Ippai Kimochi Yoku Natte ne~ | 2008-07-04 | 6.10 (19) |
| Okitsune Relaxation Yukino | 2023-04-01 | - |
| Okitsune Summer ~Natsu Gasshuku Onna no Ko Tsuki~ | 2006-12-22 | 7.00 (7) |
| Okitsune-sama ni Onegai | 2004-05-04 | - |
| Okitsune-sama no Ongaeshi | 2021-12-07 | - (1) |
| Okki Shita Asoko, Shibotte Ii Desu ka? ~Heiwa na Sekai no Monster Kaigo Seikatsu~ | 2021-03-05 | 5.60 (18) |
| Oko-sama wa Chijo | 2010-10-30 | - |
| Okoru to Shinimasu. | 2022-02-24 | - (2) |
| Okosama Packncho ♪ | 2006-08-13 | - |
| Okoshite! Narita-kun | 2012-09-13 | - |
| Okowa ~Santa~ | 2015-05-28 | - |
| Okozukai de Tsutte Chiisana Onna no Ko ni Seiteki na Itazura o Shite Mita | 2013-02-07 | - (4) |
| Okssaebat Saitkkilro | 2014-02-17 | - (2) |
| Oku-sama Nikki | 2005-12-30 | - (2) |
| Oku-sama Uchuu | 2008 | - |
| Oku-sama no Kaifuku Jutsu | 2022-05-27 | 6.70 (377) |
| Oku-sama wa Macho!! | 2013-10-27 | - |
| Oku-sama wa Marugakusei | 2006-08-13 | 6.80 (15) |
| Oku-sama wa Miko? | 2001-04-27 | 6.30 (6) |
| Oku-sama wa Moto Yariman -Besluted- | 2012-12-07 | 6.70 (196) |
| Oku-sama wa Moto Yariman 2022 | 2022-12-24 | 7.30 (151) |
| Oku-sama wa S-Jou ~Fun! Konna Koto Sarete Yorokobu Nante Anata tte Hontou ni Saitei no Otoko no Kuzu ne! Shikatanai Kara Motto Ijimete A-ge-ru♪~ | 2010-03-26 | 6.10 (7) |
| Oku-sama wa Taiikudaisei | 2007-07-21 | - |
| Oku-sama wa Zansatsu Shoujo | 2007-03-30 | 6.40 (17) |
| Oku-sama x Oku-sama ~Hanayome wa Joshikousei~ | 2006-04-28 | 6.80 (19) |