Kurofune Ballad is an experienced Melos Warrior who serves as a catalyst for the protagonist Bocca Serenade's awakening. He is the first such warrior to appear in the story, crossing paths with Bocca at the shop of their mutual acquaintance Tsunagi. In terms of appearance, he is an adult male with medium-length purple hair and blue eyes. Unlike many Melos Warriors who carry a traditional bow, Ballad fights with a crossbow or bow gun. He pilots a sentient Aibar machine named Jaguar Sun, and his Melos tattoo, the mark of a warrior, is located on his left arm. The vocal command he uses to unleash his Melos arrow is "Flush," the same command later adopted by Bocca.

Ballad's role is primarily that of an inspirational figure and a temporary ally. His battle with the monster Hor, who has just consumed a child, exposes Bocca to the hidden war between humanity and monsters and allows Bocca to hear the Melody of Oblivion for the first time. When Hor returns to threaten Bocca's town, Ballad fights alongside Bocca and the pickpocket Sayoko Tsukinomori to repel the creature. Afterward, he departs on his own, explicitly warning Sayoko not to follow him, which underscores his solitary nature. Despite this warning, Bocca and Sayoko decide to trail him, making Ballad's path the initial driving force behind their journey. Later portions of the series bring him back into the narrative during a labyrinth where time and space are distorted, a setting in which Bocca is able to encounter both the child sacrifice Solo and Ballad himself.

His personality, while not extensively detailed, projects a quiet, resolute demeanor. He does not seek companionship and seems comfortable operating alone, yet his actions reveal a sense of duty to protect others and to confront monsters. As a Melos Warrior, his core motivation is the struggle against the monstrous rulers of the world, guided by the phantom girl known as the Melody of Oblivion. His most significant relationship is with Bocca, whom he inadvertently mentors by example; Bocca's decision to become a Melos Warrior is directly inspired by witnessing Ballad in combat. Beyond that, Ballad's character remains a stable, stoic presence, providing a benchmark of what a seasoned warrior can be without undergoing a dramatic arc himself.