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| One With the Snow | 2021-12-11 | - (1) |
| One and Only | 2002-12-27 | - (1) |
| One date with a snake boy | 2022-04-02 | 5.40 (5) |
| One day | 2003-11-03 | - |
| One day of spring break with her | - | - |
| One day with 1701 | 2024-05-07 | - (3) |
| One in One Million | - | - |
| One more Chance!! | 2013-03-18 | - |
| One of Won Won -The One of Wonwon- | 2007-12-03 | - (1) |
| One to Three: Sovereignty | - | - (1) |
| One x Shota | 2012-06-07 | 6.80 (28) |
| One ~Sekai de Tada Hitori Boku no Kimi wa Hitori Dake~ | 2003-08-17 | - (3) |
| One → Shota ← One | 2020-11-27 | 7.30 (108) |
| One ☆ Boku - Faraway so close! ~Onee-chan to Boku~ | 2005-08-26 | 7.00 (12) |
| One&Only | 2002-12-30 | - |
| One's First Love | 2000-11-24 | - (2) |
| One's Inside | 2012-10-07 | - (2) |
| One's Lonesome, Two's Company | 2018-11-02 | 6.90 (28) |
| One's Own [or very] | 2000-09-15 | - (2) |
| One, Two, Three Fiancées?! | 2023-09-25 | - (2) |
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| One-Eyed Lee: Prologue | 2017-06-17 | 6.10 (7) |
| One-Hit Wonder | - | - (3) |
| OneDayOne | - | - (1) |
| OneLove R ~ONE LOVE Recover~ | 2007-02-04 | - (3) |
| OneLove ~ONE LOVE~ | 2006-04-02 | - (1) |
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| Onedari Suru made Yatte Yaru Origosino...4th | 2010-11-19 | - |
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| Onee no Koisuru Nanokakan ~Manatsu no secret love~ | 2018-08-10 | - |
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| Onee-chan (tachi) wa Osewa Saretai! | 2023-06-30 | 6.40 (42) |
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| Onee-chan Cube | 2003-07-25 | - (4) |
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| Onee-chan Hunters! Boku-tachi o Koufun Saseru Onee-chan ga Waruinda! Natsuyasumi Hen | 2012-10-04 | 6.60 (68) |
| Onee-chan Hunters! Boku-tachi o Koufun Saseru Onee-chan ga Waruinda! Tokonatsu Beach Hen | 2016-08-05 | 6.60 (55) |
| Onee-chan Maid no Gohoushi Time ~Himitsu Nan Dakara ne~ | 2010-08-13 | 6.40 (12) |
| Onee-chan Ponpon | 2009-06-09 | 5.90 (7) |
| Onee-chan Video | 1997-09-06 | - (2) |
| Onee-chan Video SE | 2000-09-08 | - (3) |
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