The episode begins with the introduction of the newly produced Medic units – the Brain Eater – by King Takuto. These eccentric, human-possessed units, which receive the names Ichiro, Jiro, and Saburo from Takuto, are selected as guardians for the twin sisters Maria and Caria, who are embarking on their first diplomatic mission to Dragontan. Their task is to explore the city, observe the culture, and simultaneously be able to go undercover.

In Dragontan, the twins and their guardians are received by Mayor Antelise, who is initially impressed by their aura and significance as future leaders of Mynoghra, but also concerned. She decides to personally guide them through the city to leave a positive impression and strengthen relations, while simultaneously neglecting her own administrative duties. During the tour, the unique abilities of the twins are revealed: Maria shows empathetic abilities that allow her to perceive the fears and worries of the citizens, while Caria demonstrates diplomatic skill and analytical thinking when she discovers forbidden Popil Grass plants.

The plot escalates when the criminal drug dealer Vesta confronts the group and offers the twins a partnership in cultivating Popil Grass, which they firmly reject. When Vesta attempts to threaten them with a concentrate of the grass and insults Takuto, Caria and Maria give the order to eliminate him. The Brain Eater Medics reveal their true nature and kill Vesta and his henchmen in a cruel manner, shocking Antelise, but also relieving her, as he was a burden on the city.

The episode ends with the group's return to Mynoghra and the implication that this mission lays the foundation for future diplomatic relations and possible expansion, while the unique abilities of the characters have been further developed.