In the manga industry, there is a legend: If you leave a message on a bulletin board at a Shibuya train station, you can obtain the services of a certain man: Comic Master J, an assistant mangaka who can instantly complete any publication manuscript in any art style for the price of 5 million yen. However, he refuses to work on manga without a "soul." But what is J's true identity? Why does he wear an overcoat lined with pens and rulers? And for what reason does a man of such artistic talent choose to live in the shadows of the industry, rather than working on a manga of his own creation?

The Devil King and his friends check out a wedding venue, buy swimsuits to work at the beach and…get marooned on a desert island?! This collection of original comic stories, drawn by a lineup of artists and fans of the series, collects episodes which may, or may not, have taken place during the main story! (Source: Yen Press)

Mobile Suit Gundam U.C. 0094: Across The Sky is a manga illustrated by Katsumoku, and officially launched in the December issue of magazine series Gundam Ace. (Source: Gundam Wikia)

From Gutsoon!: 20XX and Japan's economy suffers as the country's government begins to fail due to inadequate politicians. Seeking a dramatic restructuring of its fragile political system, the nation elects Sakuragi Kenichiro - a man educated in America- to be its first President. Given decision making powers the equivalent of a U.S. President, the young politician is faced with several international crises, including the invasion of North Korea into South Korea and China initiating attacks on Taiwan. As the "First President" he struggles against phenomenal challenges and along with his "fighting cabinet," Sakuragi works to reform Japan.

Expert soldier Taiga has just retired from the military after twenty years of service. Listless, he decides a visit to his homeland of Japan will help him figure out what to do next. But he never arrives. A strange earthquake in the airport seems to spell his demise, but instead it transports him to Million Dungeon, a labyrinthine world of caverns, kingdoms, magic...and monsters. The key to survival is apparently creating his own nation, but even with all of Taiga’s experience, the incredible dangers may prove too much... (Source: Yen Press)

Mami has tried marriage once and failed, so now she's looking for something else. Even if her peers won't get it, she wants what she wants: not marriage, not romance, just a man to spend time with when she needs some company! Sure enough, when she brings this up at her junior high class reunion, her friends all gang up against her. However, a handsome former classmate she'd almost never spoken to before—Nakamura—does empathize with her! When Mami learns that Nakamura is also once-divorced and, just like her, is looking not for a wife or a girlfriend but just a woman to spend time with, she makes a life-changing decision. She's given up on living her life according to what's "normal." After spending thirty-some years toiling under the crushing weight of societal expectations, one woman finds herself a partner in crime and a new lease on life in this modern-day survival story. (Source: MangaPlaza)

Series which followed the oneshot of the same name.

The story of Kidou Senshi Gundam: Operation:Troy opens with the space colonists' brutal battle for independence from The Earth Federation. Advanced ECM has rendered range sensors and communications useless, resulting in the rise of new war machines called mobile suits. These ultimate instruments of destruction, capable of metal-clashing hand-to-hand combat, completely redefine modern warfare. (Source: Gundam Wikia)

This tale is set at a small hot springs inn where a samurai is relaxing when he is asked to share his room. His new roommate appears to be none other than Musashi Miyamoto. (Source: Anime News Network) *Note: Published in Monthly Manga Garo No. 12 (August 1965).*