| Omaera Zenin Mendokusai! |  | For some reason, Kunitachi Kunihiko, a language arts teacher, always finds himself quarreling with his student, Kazumiya Kazumi, an anti-social girl without any friends. When he tells her to make some friends, she declares: "Be my friend, Sensei." |
| One Outs |  | The story begins when Hiromichi Kojima, the star batter of the fictional Lycaons in Japans Pacific League, heads to the southern Japanese island of Okinawa to train and bring himself out of a slump. There, he meet T?a Tokuchi, a 134-kmph (83 miles per hour) pitcher and the undisputed king of... |
| Owari no Seraph |  | Set in the near future, in a world where humans have to fend against vampires. Having lost everything during one such attack, Hyakuya Yuuichirou aims to join a specialized military squad for the sake of revenge, even as more unnatural things begin to occur... Owari no Serafu
Seraph of the... |
| Onepunch-Man (ONE) |  | Follows the life of an average hero who manages to win all battles with only one punch. This ability seems to frustrate him as he no longer feels the thrill and adrenaline of fighting a tough battle, which leads to him questioning his past desire of being strong. |
| Okusama ga Seito Kaichou! |  | The story begins with Izumi Hayato running to be student body president. But when a beautiful girl swings in promising the liberalization of love while flinging condoms into the audience, he ends up losing to her and becoming the vice president. At the student council meeting, the... |
| Ouroboros |  | At first glance Ryuzaki Ikuo, a detective in the Shinjuku Police Department’s 2nd detective unit, & Danno Tatsuya, a high ranking member of the Matsuo Yakuza clan have nothing in common. However they both are working themselves up the ladder in their respective careers for one reason... |
| Overlord |  | The story begins with Yggdrasil, a popular online game which is quietly shut down on its last day. Our protagonist Momonga decided to stay until the last moment in his beloved game and wait for the force logout. Unexpectedly, the server did not shut down and Momonga is stuck in his skeleton body... |
| One Piece |  | Gol D. Roger was known as the Pirate King, the strongest and most infamous being to have sailed the Grand Line. The capture and death of Roger by the World Government brought a change throughout the world. His last words before his death revealed the location of the greatest treasure in the world,... |
| Only Sense Online |  | Utilizing a system called "Sense," each player aims to create their unique character in the VRMMORPG "Only Sense Online." Joining this realm is Yun, an absolute beginner in the world of gaming, equipped with some of the worst customized "Sense" ever. While his two sisters, both veterans in this... |
| Otome Sensou |  | The story begins in 1420, right as what would be known as the Bohemian War began. A young girl named Sharka is raped and left for dead among the corpses of her whole town, but she manages to survive. She is picked up by the Bohemian forces, who put a gun in her hands and take her on board as a... |
| One Piece Omake |  | One Piece Omake are short manga chapters originally published in the One Piece Log Books & Databooks. |
| Ore to Kawazu-san no Isekai Hourouki |  | Tarou was just an ordinary university student until a strange old magician summoned him to another world. Upon learning that his newly acquired magical power is 8 million (8 million more powerful than an average magician), he uses his abnormally powerful magic to revive the old man that caused all... |
| Ore ga Ojou-sama Gakkou ni "Shomin Sample" Toshite Rachirareta Ke |  | In a hidden school surrounded by mountains, young ladies of good families are taught everything a high class lady needs to know. They are also completely cut off from the outside world, keeping them sheltered and innocent. However, a problem has come up recently-- more and more graduates are... |
