"Tying the Knot with an Amagami Sister" centers around Uryuu Kamihate, a young man who, after being orphaned, is taken in by the Amagami family, a lineage of shrine maidens with deep spiritual ties. The Amagami family consists of three sisters—Asahi, Yae, and Yuna—each possessing unique personalities and responsibilities tied to their shrine duties. Uryuu’s arrival disrupts their routine as he becomes entangled in their lives and the supernatural forces surrounding the shrine.

The narrative explores Uryuu’s integration into the Amagami household and his growing relationships with the sisters. Asahi, the eldest, is responsible and nurturing, often acting as the family’s anchor. Yae, the middle sister, is cheerful and energetic, bringing levity to the household. Yuna, the youngest, is reserved and introspective, often grappling with her role in the family’s spiritual legacy. Uryuu’s presence introduces a dynamic shift, as his outsider perspective challenges the sisters’ established routines and beliefs.

The plot intertwines slice-of-life elements with supernatural themes, as the Amagami shrine is a focal point for spiritual activity. Uryuu and the sisters encounter various yokai and deities, leading to episodic adventures that blend humor, drama, and light-hearted romance. The series delves into themes of family, duty, and personal growth, as each character navigates their roles within the shrine and their evolving relationships with one another.

Romantic undertones emerge as Uryuu’s bond with each sister deepens, creating a central tension in the story. The narrative avoids overt melodrama, instead focusing on the gradual development of these relationships within the context of their shared responsibilities and the shrine’s spiritual significance. The interplay between the mundane and the mystical forms the backbone of the series, offering a balanced mix of emotional depth and lighthearted moments.