See Aozora Bunko
- 'on'narashisa' to hananika (What is feminite) by Akiko Yosano (December 7,1878 - May 29,1942)
- Oborekaketa kyoudai by Takeo Arishima (March 4,1878 - June 9,1923)
- Oboro by Kanoko Okamoto (March 1,1889 - February 18,1939)
- Ochikubo monogatari translated by Satoru Hase
- Odoru chiheisen (Dancing horizon) by Joji Tani (January 17,1900 - June 29,1935)
- Ogata Ryousai oboegaki (Ogata Ryousai's memo) by Ryunosuke Akutagawa (March 1,1892 - July 24,1927)
- Ogawa Usen sensei to watashi (Mr. Ogawa Usen and me) by Ujo Noguchi (May 29,1882 - January 27,1945)
- Ogawa Usen by Bocho Yamamura (January 10,1884 - December 8,1924)
- Ogin by Ryunosuke Akutagawa (March 1,1892 - July 24,1927)
- Ogumahideo zenshuu-01 by Hideo Oguma (September 9,1901 - November 20,1940)
- Ogumahideo zenshuu-02 by Hideo Oguma (September 9,1901 - November 20,1940)
- Ogumahideo zenshuu-03 by Hideo Oguma (September 9,1901 - November 20,1940)
- Ogumahideo zenshuu-04 by Hideo Oguma (September 9,1901 - November 20,1940)
- Ogumahideo zenshuu-05 by Hideo Oguma (September 9,1901 - November 20,1940)
- Ogumahideo zenshuu-06 by Hideo Oguma (September 9,1901 - November 20,1940)
- Ogumahideo zenshuu-07 by Hideo Oguma (September 9,1901 - November 20,1940)
- Ogumahideo zenshuu-08 by Hideo Oguma (September 9,1901 - November 20,1940)
- Ogumahideo zenshuu-09 by Hideo Oguma (September 9,1901 - November 20,1940)
- Ogumahideo zenshuu-10 by Hideo Oguma (September 9,1901 - November 20,1940)
- Ogumahideo zenshuu-11 by Hideo Oguma (September 9,1901 - November 20,1940)
- Ogumahideo zenshuu-12 by Hideo Oguma (September 9,1901 - November 20,1940)
- Ogumahideo zenshuu-14 by Hideo Oguma (September 9,1901 - November 20,1940)
- Ogumahideo zenshuu-20 by Hideo Oguma (September 9,1901 - November 20,1940)
- Ohagi to nanakusagayu by Hajime Kawakami (October 20,1879 - January 30,1946)
- Ohisama no aruuchini by Terence Rattigan (1911 - 1977)
- Oitaru susanoonomikoto by Ryunosuke Akutagawa (March 1,1892 - July 24,1927)
- Ojigi by Ryunosuke Akutagawa (March 1,1892 - July 24,1927)
- Ojiisan'no Lamp (Grandfather's lamp) by Nankichi Niimi (July 30,1913 - March 22,1943)
- Okamoto Ippei cho narabiniga "Tanbougashu" jo by Soseki Natsume (February 9,1867 - December 9,1916)
- Okashi no daibutoukai (The ball of candies) by Kyusaku Yumeno (January 4,1889 - March 11,1936)
- Okinagusa by Kenji Miyazawa (August 27,1896 - September 21,1933)
- Okujou no kyoujin (Zanist on the roof) by Kan Kikuchi (December 26,1888 - March 6,1948)
- Okusama tanteijutsu (Housewife's detective skill) by Kyusaku Yumeno (January 4,1889 - March 11,1936)
- Omoidasukoto nado by Soseki Natsume (February 9,1867 - December 9,1916)
- Omoide jojoushoukyokushuu by Hakushu Kitahara (January 25,1885 - November 2,1942)
- Omoidenoki by Setsuko Koizumi (1868 - 1932)
- Omokage by Yuriko Miyamoto (February 13,1899 - January 21,1951)
- Omoshiroki niko no koukoku by Toshihiko Sakai (November 25,1871 - January 23,1933)
- On'na hyakkaten (Women's grocery store) by Eisuke Yoshiyuki (May 10,1906 - July 8,1940)
- On'na no kao (Women's face) by Seiki Kuroda (June 29,1866 - July 15,1924)
- On'na no kettou (Women's battle) by Osamu Dazai (June 19,1909 - June 13,1948)
- On'na (Women) by Ryunosuke Akutagawa (March 1,1892 - July 24,1927)
- On'na (Women) by Senko Mizuno (December 3,1888 - May 31,1919)
- On'nakeizu by Kyoka Izumi (November 4,1873 - September 7,1939)
- On wo kaesu hanashi by Kan Kikuchi (December 26,1888 - March 6,1948)
- onashiinu by Ryoji Sano (b.1940)
- Onchi by Kyusaku Yumeno (January 4,1889 - March 11,1936)
- Ongaku no hanhouhouronjosetsu by Yuji Takahashi (b.1938)
- Onjou no yutakananatsumesan by Roan Uchida (April 5,1868 - June 29,1929)
- Onmi by Riichi Yokomitsu (March 17,1898 - December 30,1947)
- Onsen'yado no niwa by Bokusui Wakayama (August 24,1885 - September 17,1928)
- Onsen (Hot spring) by Motojiro Kajii (February 17,1901 - March 24,1932)
- Onsendayori (Hot spring jounary) by Ryunosuke Akutagawa (March 1,1892 - July 24,1927)
- Onshuu no kanatani by Kan Kikuchi (December 26,1888 - March 6,1948)
- Ookawanomizu by Ryunosuke Akutagawa (March 1,1892 - July 24,1927)
- Oosaka mangekyou (Osaka kaleidoscope) by Eisuke Yoshiyuki (May 10,1906 - July 8,1940)
- Oosaka no chounin-gakusha Tominaga Nakamoto by Konan Naito (July 18,1866 - June 26,1934)
- Oosaka no chounin to gakumon by Konan Naito (July 18,1866 - June 26,1934)
- Oosakahakken (The discovery of Osaka) by Sakunosuke Oda (October 26,1913 - January 10,1947)
- Ooshima ga dekiru hanashi by Kan Kikuchi (December 26,1888 - March 6,1948)
- Ooshio Heihachirou by Ogai Mori (February 17,1862 - July 9,1922)
- Ootomoyakamochiron'ichi by Shuzo Machino (b.November 18,1943)* ootomoyakamochiron'ichi by Shuzo Machino (b.November 18,1943)
- Ootsugomori by Ichiyo Higuchi (May 2,1872 - November 23,1896)
- Orient no shita (Orient's tongue) by Kazuko Fujimoto (b.1939)
- Orinposu no kajitsu by Hidemitsu Tanaka (January 10,1913 - November 3,1949)
- Oritsu to korato (Oritsu and children) by Ryunosuke Akutagawa (March 1,1892 - July 24,1927)
- orokanaru(?!)haha no sanbunshi by Kanoko Okamoto (March 1,1889 - February 18,1939)
- Osai no nai bentou (Lunchbox without vegetables) by Mutsuo Honjo (February 20,1905 - July 23,1939)
- Osan by Osamu Dazai (June 19,1909 - June 13,1948)
- Oshaberi hime by Kyusaku Yumeno (January 4,1889 - March 11,1936)
- Oshaku by Kanoko Okamoto (March 1,1889 - February 18,1939)
- Oshare douji by Osamu Dazai (June 19,1909 - June 13,1948)
- Oshie no kiseki by Kyusaku Yumeno (January 4,1889 - March 11,1936)
- Oshino by Ryunosuke Akutagawa (March 1,1892 - July 24,1927)
- Osoroshiki tsuya by Juza Unno (December 26,1897 - May 17,1949)
- Oto nitsuite by Osamu Dazai (June 19,1909 - June 13,1948)
- Otogizoushi by Osamu Dazai (June 19,1909 - June 13,1948)
- Otoko gokoro toha koushitamono by Kanoko Okamoto (March 1,1889 - February 18,1939)
- Otomi no teisou by Ryunosuke Akutagawa (March 1,1892 - July 24,1927)
- Otuberu to zou (Otuberu and Elephant) by Kenji Miyazawa (August 27,1896 - September 21,1933)
- Ougon fuukei by Osamu Dazai (June 19,1909 - June 13,1948)
- Oujou emaki by Ryunosuke Akutagawa (March 1,1892 - July 24,1927)
- Ounin' no ran' ni tsuite (About Ounin' no ran') by Konan Naito (July 18,1866 - June 26,1934)
- Ousemadeno by Masato Uematsu (b.1962)
- Ouson sensei genkouroku by Osamu Dazai (June 19,1909 - June 13,1948)
- Outou by Osamu Dazai (June 19,1909 - June 13,1948)
- Oyatoiu niji (Two character parent) by Osamu Dazai (June 19,1909 - June 13,1948)
- Ozaki Housai senkushuu by Hosai Ozaki (January 20,1885 - April 7,1926)