Moritaka Mashiro, an average student with a talent for drawing, forgets his notebook at school, where his classmate Akito Takagi finds and looks through it. Takagi likes his drawings and asks Mashiro to team up with him to create a best-selling manga. Mashiro refuses because his uncle was a manga artist until he died from overworking, while deeply in debt, which derails his dream. Takagi soon invites him to visit Miho Azuki, the girl Mashiro has an unrequited crush on, and Takagi tells her of his plan to create a manga that will become an anime, in which she will play the heroine. Mashiro also proposes to marry Azuki when both their dreams come true, and she agrees that they will, but shall not see each other until then. With this motivation, Mashiro decides to become a manga artist.
Mashiro and Takagi arrive at Mashiro's uncle's apartment, where they look around and Mashiro shows Takagi the manuscripts and storyboards, that the author of a manga series produces before drawing it. Mashiro realizes that his uncle was working extremely hard until his death and vows to approach it with the same resolve. Mashiro and Takagi find letters between his uncle and his friend from childhood, which stop before his hit manga was serialized, and looking at a yearbook photo of her, realized that he had been in love with Azuki's mother. They go to visit Azuki's mother the next day, and learn that she was also in love with him, but never could admit it and fell in love with someone else. Mashiro asks Azuki's mother not to tell her about the relationship between her and her uncle, and he then sets out to make a manga.
Mashiro and Takagi meet with Akira Hattori, one of the editors at Shonen Jack. He notes that their work has flaws, as it is too text-driven and not drawn in manga style, but they have potential. He tells them that they are better suited to figuring out what could be a hit and drawing that, rather than drawing what they want, and while they are less likely to get a smash hit with that skillset, they are more likely to follow up on one if they do. Hattori gives them his contact information, encouraging them to come to him with their work. At school, the teacher decides to seat boys and girls next to each other, resulting in Mashiro sitting next to Azuki.
Recalling when he and Azuki turned back to look at each other at the same time, Mashiro tells Takagi that he and Azuki have been on the same frequency for years, indicating that they are connected without having to say anything about it. Azuki's best friend Kaya Miyoshi goes to Takagi to complain about him telling Azuki about her dream, and as she does so, gives indications of romantic interest in Takagi that Mashiro and Miyoshi notice. During the summer, Mashiro and Takagi stay at Mashiro's uncle's office, and work on a manga called The Two Earths. When it is complete, they call the Shonen Jack editorial department.
Mashiro chats with Takagi, who tells him that he chose Mashiro because he is smarter than many of his peers in matters outside of scholarship, and that he believes Azuki has a similar kind of intelligence, with the ability to be appealling to others. Mashiro tells Takagi that he believes his uncle committed suicide, and thus suspects that his parents will oppose him becoming a manga artist. Mashiro's mother says his uncle did not commit suicide, but still opposes his decision until his father and grandfather show support for his dream. Mashiro's grandfather gives him his deceased uncle's studio apartment, and Mashiro brings Takagi to see it.
Takagi comes up with some more ideas, including One Hundred Millionth, a story about people being ranked according to their abilities, and Hattori is impressed with the story, causing Mashiro to wonder if his art is good enough. The story is chosen as one of the finalists, but does not make it to the four chosen for the award or honorable mentions. Shortly afterward, Ishizawa, a classmate, claims that Mashiro's art is holding Takagi down. Takagi gets angry and punches Ishizawa.
Mashiro shows Takagi all that he has drawn and points out all the mistakes he has made, as well as the finer points of using tools for drawing manga. When Takagi questions him, Mashiro tells him about G-Pens and Kabura pens, making manuscripts, and Taro Kawaguchi's three rules to a successful manga: conceit, doing your best, and luck. When they go to a convenience store, Takagi notices that the latest issue of Jack has a semi-finalist named Eiji Nizuma, a fifteen year old manga creator. The two discuss their high schools, manga, and editors, thus coming to the conclusion that they would finish the manuscript for a manga by summer's end and show it to an editor of Jack. While walking home with Takagi, Mashiro encounters Azuki by chance; while the two are unable to look at each other as they pass, they both turn back to look.