The Yuzuki family, which consists of four brothers, lost their parents two years ago. Hayato, the eldest son, is a hard worker and the pillar of the family. Mikoto, the second son, is calm and collected, but he has a soft spot for his younger brother Minato, whom he adores and thinks is cute. Minato, the third son, is energetic and adores his brothers, but he is clumsy and awkward. Gakuto, the fourth son, is a studious and mature first-grader who is often referred to as a "wise man." The manga depicts the four brothers' daily lives as they navigate their family, school, and community.

While walking through the forest one day, a witch named Alyssa finds a bush glowing with a magical aura. She discovers a baby who, although not a witch, possesses magic that is too strong for that of a mere human. As such, Alyssa decides to raise the child as her own, naming her Viola. Sixteen years later, Viola is all grown up and now towers over her youthful mother, and her mature looks cause many to confuse their ages. Nevertheless, Alyssa adores her child despite Viola's possessive streak and tendency to drive away anyone she fears will take away her mother's love. Viola may not be sure where she came from, though she has all she needs in Alyssa and the plethora of Alyssa's friends who have come together to raise her. Under Alyssa's guidance, Viola will learn to master her magic and make her adoptive mother proud.

The first astronaut in human history was a vampire girl. Following the end of World War II, the world-dividing superpowers, Federal Republic of Zirnitra in the East and United Kingdom of Arnack in the West, turned their territorial ambitions toward space. Both countries have been competing fiercely for development. East history 1960. Gergiev, the chief leader of the Republic, announces the manned space flight program Project Mechtat (Dream), which, if successful, would be the first feat for humankind. At that time, Lev Leps, a substitute astronaut candidate, is ordered to perform a top secret mission. The "Nosferatu Project"—a program that experiments with vampires prior to manned missions—will use Irina Luminesk as a test subject, and Lev is to monitor and train her. Even while trifled by the walls of the race and ego of the nations, Lev and Irina share a genuine sentiment as they aim for the universe. (Source: MAL News)

"To be quiet and do as you're told, that's the cowardly choice." These are the words of Junk Dog, an underground fighter of Megalo Box, an evolution of boxing that utilizes mechanical limbs known as Gear to enhance the speed and power of its users. Despite the young man's brimming potential as a boxer, the illegal nature of his participation forces him to make a living off of throwing matches as dictated by his boss Gansaku Nanbu. However, this all changes when the Megalo Box champion Yuuri enters his shabby ring under the guise of just another challenger. Taken out in a single round, Junk Dog is left with a challenge: "If you're serious about fighting me again, then fight your way up to me and my ring." Filled with overwhelming excitement and backed by the criminal syndicate responsible for his thrown matches, Junk Dog enters Megalonia: a world-spanning tournament that will decide the strongest Megalo Boxer of them all. Having no name of his own, he takes on the moniker of "Joe" as he begins his climb from the very bottom of the ranked list of fighters. With only three months left to qualify, Joe must face off against opponents the likes of which he has never fought in order to meet the challenge of his rival. [Written by MAL Rewrite]