The story begins with Nigris, a member of the S-rank adventurer party "Silver Wings," cleaning up after his companions. Despite their proximity to SS-rank, the highest tier of adventurers and a path to nobility, Nigris's role is that of a servant. His skill, [Appraisal], which allows him to view basic status information, is deemed useless in combat. Nigris joined the party out of a sense of camaraderie with fellow orphans, but his position has devolved into near slavery. The party leader, Azel, along with the magic-user Mia, the priest Ann, and the shield-bearer Augustus, reveal their intention to expel Nigris. They mock his Appraisal skill and his claim of possessing healing magic, which he had used to support them. Azel, a self-proclaimed genius swordsman, dismisses Appraisal as unnecessary for their brute-force approach. Nigris realizes his contributions, including his healing magic and efforts to support the party financially, were unacknowledged and that his companions viewed him as a parasite. He leaves the party, taking only his personal belongings, while the Silver Wings celebrate their impending SS-rank advancement. Nigris, however, knows a secret: their stats haven't improved in three years, and he had been simultaneously healing and supporting them.
The next day, Nigris, now a D-rank adventurer with meager funds, heads to the Adventurer's Guild, seeking trustworthy companions. He learns that Silver Wings spread rumors of his incompetence, making it difficult to form a new party. While en route, he witnesses a slave trader mistreating a young girl, Fels, who is suffering from a slave collar's activation. Despite the danger, Nigris intervenes, purchasing Fels for his entire fortune. He discovers Fels is an Elf with an incredibly high potential in swordsmanship (SS-rank) but is cursed, suppressing her magic. Nigris uses his healing magic to save her and then takes her to eat.
During their meal, Fels, accustomed to being a slave, struggles with basic social interactions. Nigris asserts his role as her master, encouraging her to eat and gradually shed her slave mentality. He learns Fels fled her previous master who was known to kill slaves. He also discovers her swordsmanship potential through Appraisal, noting the curse that hinders her magic. Nigris decides to remove the curse, which he identifies as man-made dark magic, and successfully dispels it using his holy-attribute healing magic. This act triggers a significant physical transformation in Fels, who grows into a young woman and her magic potential unlocks, revealing her innate power. Nigris offers Fels a choice: join him or go her own way. Fels, grateful for his kindness, chooses to stay with him, becoming his first true companion.
Nigris and Fels begin taking on quests, with Nigris focusing on Fels's growth. Fels, despite her inexperience, displays astonishing combat prowess, quickly mastering swordsmanship and even unconsciously using physical enhancement magic, making her a formidable magic swordsman. Nigris's healing magic, which he discovers can also boost allies' abilities, further enhances her performance. They successfully complete a quest, earning a modest reward. However, their success draws negative attention at the Guild, with whispers of Nigris being the "incompetent" expelled from Silver Wings. Fels fiercely defends Nigris, her loyalty now at maximum.
Later, Nigris and Fels encounter a thief. Fels effortlessly subdues him, demonstrating her rapid development. Nigris also uses his Appraisal skill on a wounded guard, advising him on his combat style. He then heals the thief, who had been injured by a monster and resorted to theft. The guard recognizes Nigris and acknowledges the falsity of the rumors surrounding him. They learn that healers are disappearing in the slums, prompting Nigris to consider moving there for a potential business opportunity and a place to stay.
Meanwhile, the Silver Wings, arrogant and overconfident, embark on a quest to hunt a B-rank monster, the Red Wolf. They are ambushed and severely injured, a stark contrast to their previous invincibility. Blaming their new, inexperienced slave companion, Azel brutally attacks and kills him. They then accept a dangerous mission from a powerful noble to assassinate the "Empress of the Slums," believing this will grant them SS-rank.
Nigris and Fels enter the slums and are brought before the Empress, Florence, a beautiful and formidable woman. Nigris appraises her and discovers she is a former slave with significant combat and magical potential, though currently cursed. Florence, initially suspicious, is intrigued by Nigris's ability to heal her deep, hidden wounds, including a slave brand. Nigris successfully removes the brand, earning Florence's respect and a place to live in the slums. He begins offering his Appraisal and advice services to Florence's subordinates, earning them gold. Fels, now fully devoted to Nigris, adopts a maid outfit and insists on serving him.
Nigris and Fels then encounter a red-haired girl named Alisa, a "Nino person" who is ostracized and bullied for her unique appearance and her sole reliance on fire magic. Nigris, recognizing her immense magical talent (SS-rank), intervenes and heals her injuries. He offers her a place in his party, and together they embark on a quest to gather herbs. During the quest, Alisa's fire magic, amplified by Nigris's healing magic, unleashes immense power, accidentally striking the nest of a formidable SS-rank monster, the Guardian Dragon, previously defeated by Silver Wings. This sets the stage for a dangerous confrontation.
