Moerus (also romanized as Melos) features in the "Run, Melos!" story adapted within the series. He is a shepherd living under the oppressive reign of King Dionysius. Driven by outrage at the king's cruelty, Melos attempts assassination but is captured. To attend his sister's wedding, he secures a three-day stay of execution by offering his friend Selinuntius as a hostage; Selinuntius faces death if Melos fails to return.

Melos's journey home confronts him with a flooded river, bandit assaults, physical collapse, and oversleeping after the wedding celebrations. These trials push him to the brink of abandoning his promise. He reclaims his resolve upon recalling Selinuntius's sacrifice and his need to defy the king's cynical view of human trust. Summoning his last strength, he races back, arriving at the execution site just in time to halt Selinuntius's death, fulfilling his pledge. Melos urges Selinuntius to punish him for his moment of doubt, while Selinuntius confesses his own fleeting loss of faith in Melos. Their reconciliation directly counters the king's worldview.

The anime frames this narrative through a framing device: a playwright crafting a stage version of "Run, Melos!" while wrestling with his own betrayal of a childhood friend. This parallel plot explores guilt and redemption, using Melos as a symbolic counterpoint to the playwright's personal failures.