"Hiiro no Kakera - The Tamayori Princess Saga" is a supernatural romance anime based on the otome visual novel series. The story centers on Tamaki Kasuga, a high school girl who moves to a rural village to live with her grandmother. Upon arrival, she discovers she is the descendant of the Tamayori Princess, a figure tasked with protecting the world from malevolent forces by sealing the Onikirimaru, a powerful demon blade. Tamaki is entrusted with this ancient duty, which involves safeguarding five magical artifacts known as the Tamayori Orbs.

To aid her in this mission, Tamaki is assigned five guardians, each possessing unique abilities tied to the elements and ancient lore. These guardians include Takuma Onizaki, a stoic and protective swordsman; Mahiro Atori, a cheerful and loyal archer; Shinji Inukai, a calm and analytical strategist; Yuuichi Komura, a kind-hearted and empathetic healer; and Suguru Oomi, a mysterious and aloof figure with a deep connection to the Onikirimaru. Each guardian has a personal stake in the mission, and their relationships with Tamaki evolve as they work together to prevent the Onikirimaru from being unleashed.

The narrative unfolds as Tamaki and her guardians face various supernatural threats, including rogue spirits and individuals seeking to misuse the Onikirimaru's power. The story explores themes of duty, sacrifice, and the bonds formed between the characters as they confront their shared destiny. Tamaki's growth as the Tamayori Princess is central to the plot, as she learns to harness her latent powers and navigate the complexities of her role. The series balances action, romance, and mystery, with a focus on the interplay between the characters and their collective struggle against the forces of darkness.

The anime adapts the visual novel's branching narrative into a cohesive storyline, emphasizing the guardians' individual backstories and their connections to Tamaki. While the series primarily follows a linear plot, it incorporates elements of the visual novel's multiple routes, offering glimpses into the potential romantic dynamics between Tamaki and her guardians. The overarching conflict revolves around the guardians' efforts to protect Tamaki and prevent the Onikirimaru from falling into the wrong hands, culminating in a climactic battle that tests their resolve and unity.