"Orient" is a manga series set in an alternate version of feudal Japan, where demons known as Oni have overrun the land, forcing humanity into subjugation. The story begins in the Awaji Island region, where the protagonist, Musashi, grows up in a world where humans are oppressed by the Oni and their human collaborators, the Bushi. These Bushi wield a mysterious power called Obsidian Crystals, which allow them to fight the Oni. However, the Bushi have abandoned their duty to protect humanity, instead serving the Oni to maintain their own power.

Musashi, a young and ambitious blacksmith, dreams of becoming a legendary warrior to free humanity from the Oni's tyranny. Alongside his childhood friend, Kojiro Kanemaki, Musashi embarks on a journey to challenge the status quo. Kojiro, initially skeptical of Musashi's ideals, eventually joins him after witnessing his determination and the atrocities committed by the Oni and their collaborators. Together, they form a band of warriors called the Obsidian Eight Blades, aiming to unite humanity and reclaim their world.

The narrative explores themes of rebellion, camaraderie, and the struggle for freedom. Musashi and Kojiro encounter various allies and enemies, including other Bushi who either oppose or support the Oni. The series delves into the complexities of power, loyalty, and the moral ambiguities of war. As the story progresses, Musashi and his companions uncover the truth about the Oni's origins and the role of the Obsidian Crystals, leading to larger conflicts and revelations about the world's history.

The characters are central to the story's development. Musashi is portrayed as a determined and idealistic leader, driven by a desire to protect the weak and challenge oppression. Kojiro, in contrast, is more pragmatic and initially reluctant to embrace Musashi's vision, but his loyalty and growth as a warrior make him a key figure in their quest. Other significant characters include Tsugumi Hattori, a skilled warrior who joins their cause, and Naotora Takeda, a Bushi with conflicting loyalties who becomes a pivotal figure in the struggle against the Oni.

The plot is structured around the group's efforts to gather allies, confront powerful enemies, and uncover the secrets of the Oni and the Obsidian Crystals. The series balances action-packed battles with moments of character development and world-building, creating a dynamic and engaging narrative. As the story unfolds, the stakes escalate, leading to larger confrontations and a deeper exploration of the world's lore and the characters' motivations.