"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, Tamaki discovers she is the descendant of the Tamayori Princess, a figure tasked with protecting the world from supernatural threats. Her role involves safeguarding the Onikirimaru, a sacred sword that seals away malevolent spirits known as the Oni.

As the Tamayori Princess, Tamaki is assigned five guardians, each possessing unique abilities tied to the elements: Takuma Onizaki, Mahiro Atori, Shinji Inukai, Yuuichi Komura, and Suguru Oomi. These guardians are bound by duty to protect her, but their personalities and backgrounds vary widely, creating a dynamic group dynamic. Takuma, the leader, is stoic and loyal; Mahiro is cheerful and optimistic; Shinji is reserved and intellectual; Yuuichi is playful and flirtatious; and Suguru is serious and disciplined. Together, they form a protective circle around Tamaki as she learns to embrace her destiny.

The narrative unfolds as Tamaki and her guardians face escalating threats from the Oni, who seek to break free from their seal and wreak havoc. The series explores themes of duty, sacrifice, and the bonds between the guardians and Tamaki, with romantic undertones as her relationships with the guardians deepen. The story also delves into the history of the Tamayori Princess and the origins of the Oni, revealing a centuries-old conflict that ties the characters together.

As the plot progresses, Tamaki must confront her own insecurities and fears while balancing her responsibilities as the Tamayori Princess. The guardians, too, face personal challenges, including their loyalty to Tamaki and their own pasts. The series blends action, romance, and supernatural elements, culminating in a climactic battle against the Oni and a resolution that tests the strength of the bonds between Tamaki and her guardians.