Chained Soldier, also known as "Mato Seihei no Slave" is set in a world where gates to a dangerous dimension called Mato open, unleashing monsters known as Shuuki that threaten humanity. In this chaotic environment, women gain supernatural powers by consuming a resource called "Peach," leading to a matriarchal society. The protagonist, Yuuki Wakura, becomes embroiled in this conflict when he meets Kyouka Uzen, the commander of the 7th squad of the Demon Defense Force, who enslaves him to utilize his newfound abilities against the Shuuki.

As Yuuki navigates his new life, he grapples with the unsettling nature of his "rewards" for helping Kyouka and her squad. The story explores themes of power dynamics and gender roles within its action-packed narrative, often intertwining combat with provocative situations. Despite its controversial elements, the manga has garnered attention for its unique premise and character interactions, though it also faces criticism for its portrayal of relationships and reliance on fanservice.