"Million Arthur" is a fantasy anime series based on the mobile game of the same name. The story is set in a medieval-inspired world where the legendary sword Excalibur has been shattered into multiple fragments. According to prophecy, only the true King Arthur can wield the sword's full power, but the sword's fragmentation has led to a crisis, as multiple individuals claim the title of Arthur, each believing themselves to be the rightful ruler. The central conflict revolves around these claimants, known as "Million Arthurs," who must gather the scattered fragments of Excalibur to prove their legitimacy and restore peace to the land.

The narrative follows a group of Arthurs, each representing a distinct class or archetype, as they embark on a quest to retrieve the Excalibur fragments. Among them are Danchou Arthur, a straightforward and determined leader; Tekken Arthur, a martial artist with a strong sense of justice; Yamaneko Arthur, a cunning and resourceful thief; Renkin Arthur, a skilled alchemist with a mysterious past; Kakka Arthur, a noble and refined aristocrat; and Kiruma Arthur, a cheerful and optimistic merchant. Each character brings unique abilities and perspectives to the group, contributing to their dynamic interactions and growth throughout the series.

As the Arthurs journey across the land, they encounter various challenges, including rival Arthurs, powerful monsters, and political intrigue. The fragmented nature of Excalibur serves as a metaphor for the fractured state of the world, with each fragment representing a piece of the kingdom's unity and strength. The series explores themes of leadership, identity, and the responsibilities that come with power, as the Arthurs grapple with their own motivations and the consequences of their actions.

The plot is driven by both external conflicts and internal struggles, as the characters confront their doubts and insecurities while striving to fulfill their roles as potential rulers. The series balances action-packed battles with moments of character development, offering a mix of humor, drama, and adventure. The overarching goal of restoring Excalibur and determining the true Arthur serves as the narrative backbone, tying together the individual arcs of the characters and their shared journey.

Throughout the series, the Arthurs face moral dilemmas and ethical questions, challenging their understanding of what it means to be a leader and a hero. The story emphasizes the importance of cooperation and mutual respect, as the characters learn to work together despite their differences. The resolution of the series hinges on their ability to unite their strengths and overcome the obstacles that stand in their way, ultimately determining the fate of the kingdom and the legacy of Excalibur.