"Conception" is a 12-episode anime series that adapts the premise of the 2012 role-playing game of the same name. The story centers on Itsuki Yuge, a high school student who is unexpectedly transported to the magical world of Granvania. This world is plagued by a phenomenon known as "Impurity," which corrupts the land and its inhabitants. Granvania's salvation hinges on the Star God, a prophesied savior capable of purifying the Impurity. Itsuki is identified as the Star God's descendant and is tasked with fulfilling this role.

To combat the Impurity, Itsuki must collaborate with twelve Star Maidens, each representing a zodiac sign and possessing unique magical abilities. The process of purifying the Impurity involves a ritual called "Classmating," where Itsuki and a Star Maiden form a deep spiritual bond, resulting in the birth of Star Children. These children are imbued with the power to cleanse the corrupted areas of Granvania. The narrative explores Itsuki's journey as he builds relationships with the Star Maidens, navigates the challenges of leadership, and confronts the growing threat of the Impurity.

The main characters include Itsuki Yuge, the protagonist, who is initially reluctant but grows into his role as the Star God's descendant. The Star Maidens, such as Mahiru, the diligent and responsible Aries maiden, and Serina, the cheerful and optimistic Sagittarius maiden, each bring distinct personalities and abilities to the group. Other key figures include Torie, the guardian of the Star God's shrine, who guides Itsuki, and Narugino, a mysterious girl with a connection to the Impurity.

The plot progresses through Itsuki's efforts to purify Granvania by forming bonds with the Star Maidens and raising Star Children. Along the way, the group faces various trials, including battles against Impurity-corrupted creatures and internal conflicts within the team. The series balances action, fantasy, and character-driven moments, with a focus on Itsuki's growth and the evolving dynamics between him and the Star Maidens. The narrative concludes with a resolution to the central conflict, though it leaves room for further exploration of the world and its characters.