The compilation film will recap the anime's 59 episodes from seasons one to three.

Despite having no real combat talent, kind 15-year-old Kurt Rockhans belongs to the famous party Flaming Dragon Fang. He is perfectly satisfied as the party's helper—until the other members kick him out and replace him with a stronger ally. Left without a way to provide for himself, Kurt begins searching for a job. With his job prospects limited by his lack of combat ability, Kurt gladly accepts any work that comes his way. During one such job, he meets Yulishia, an adventurer formerly employed by the royal family. Surprised by Kurt's impressive work, Yulishia discovers that he is no ordinary boy: Kurt possesses an astonishingly high aptitude in a variety of non-combat fields. Due to these talents, a court official tells Yulishia to offer Kurt a high status in the kingdom that would allow him to live in peace for the rest of his life. When Yulishia informs Kurt about his potential rank, he brushes off the offer, refusing to think of himself as above other people. Still unaware of his real power, Kurt continues taking as many odd jobs as possible, which might just make him a pivotal part of the kingdom before he even notices it.

Nestled away on the rooftop of Tenikai General Hospital is the unconventional Department of Investigative Pathology headed by the eccentric Dr. Takao Ameku. The tiny department, consisting of Takao and her sole resident Yuu "Kotori" Takanashi, treats complex cases that most other departments within the hospital cannot resolve on their own. The mystery-obsessed Takao always tries to insert herself into cases that capture her fancy—much to the dismay of her colleagues and the police. Even if her meddling creates more problems for the hospital and those around her, none can deny the brilliance that the young department head exhibits as she weaves a diagnosis together. No matter the specialty, no case is impossible for Takao and a somewhat reluctant Takanashi to solve.

There are some things that people are unable to say while they are alive; for these, there are "shigofumi," letters carried from the world of the dead to the world of the living. When a person with strong emotions dies, they are able to create a shigofumi, whether their feelings are of love, longing, or resentment. It is the quiet and mysterious Fumika's job to deliver these messages from the departed. Along with her talking magic staff Kanaka, she ensures that each shigofumi reaches its intended recipient, even if that person does not want to face its contents. Fumika witnesses the tragedies of people, both dead and alive, and sees their deepest secrets revealed. What is unclear, however, are the details of Fumika's past. Who was she before she came to be a carrier of shigofumi?