The story begins with Lily Orlando, an eighteen-year-old who claims to be an ordinary girl with no romantic experience. However, she reveals that for the past three years, she has been living in the deepest level of a certain labyrinth for reasons she will explain.
Lily recounts her past as an adventurer with her childhood friends: Adol Rozzo (swordsman, leader), Quoria Cornell (black mage), Karia Torus (heavy knight), and Zepetto Rururan (archer). At twelve, individuals receive a divine occupation, such as warrior or farmer. Lily's occupation was "White Mage," specializing in healing, which is valuable for its ability to mend injuries without potions, though it consumes her magic.
The reason for her current predicament lies in the world's "status" system, where experience gained from defeating monsters increases levels and stats. Crucially, one must inflict damage on monsters to gain experience. As a White Mage, Lily had limited offensive capabilities, her light magic being weak compared to a black mage's, and her physical attacks ineffective against stronger foes. This led to White Mages being considered an "unfortunate profession" for adventurers. Despite this, Lily pursued adventuring with her friends, dreaming of becoming the strongest party and exploring the world. This dream shattered three years prior.
The turning point occurred when Adol informed Lily that her healing magic was no longer useful, as potions were more efficient, and he intended to expel her from the party after their next request, regardless of their childhood bond. Though aware of her perceived inadequacy, Lily agreed to join them for one last job, driven by a desire to be with them. They entered the Orphenok Underground Labyrinth, known for its powerful monsters.
During their expedition, they were ambushed by an Orthros, a two-headed wolf monster, pushing the party to the brink of annihilation. Adol proposed a plan: Lily would be the decoy while the others escaped. Lily, unable to keep up due to the stat difference, was targeted by the Orthros. She narrowly escaped, using all her luck, but then fell into a deep, dark hole due to exhaustion.
Miraculously, Lily survived the fall, waking up on a bed in an unknown room. She found herself in the deepest level of the Orphenok Underground Labyrinth, a place where monsters did not approach. Unable to return to the surface, she decided to live there. After three years, Lily, now Level 1082 and a "Saint Sorceress" with an astonishing array of skills and stats, has decided to attempt to return to the surface. Her transformation into a "Saint Sorceress" required fulfilling conditions for both "White Mage" and "Black Mage" to evolve into their higher forms, "Saint" and "Witch" respectively, a feat she achieved through unknown means, possibly related to a book she found. Her title, "Seeker of Magic," was earned by using magic 100,000 times.
Lily's journey upwards begins. She encounters a Death Scythe, a skeleton monster with a scythe that inflicts instant death. Despite its abilities, Lily's high stats and automatic magic barrier, derived from her "Saint Sorceress" occupation, easily deflect its attacks. She defeats the Death Scythe and its summoned skeletons with a powerful ice magic spell, "Absolute Zero."
Continuing her ascent, Lily reaches the 390th floor, the location of the final floor boss. She strategically enters the boss room from behind, catching the "Catastrophe Dragon" off guard. After weakening it with her dark magic and overwhelming it with a barrage of spells, Lily decides not to kill it. Instead, she uses healing magic to revive it, intending to make it her companion. To her surprise, a contract is automatically formed, and the dragon transforms into a small, cute dragon named Tart.
With Tart, Lily continues her journey upwards. Tart, despite its reduced stats, proves to be an invaluable combatant, allowing Lily to conserve her magic. They encounter a large lake, which Lily freezes with "Absolute Zero" and then uses her magic to create ice skates, enjoying a brief moment of recreation before continuing their ascent. They discover a treasure chest containing a "Black and White Mask," an item with minor utility.
As they progress, Lily notes that monsters become weaker on higher floors. She also reflects on the loss of her adventurer's license, which expired, causing her to lose all her accumulated savings. She also considers the possibility that her former party members might have used her saved money. Tart's presence provides Lily with comfort and support, helping her overcome her lingering resentment.
Lily and Tart continue their journey, with Tart's combat prowess significantly aiding their progress. They encounter a large lake, which Lily freezes and then uses to practice ice skating, a new skill she develops. They discover a treasure chest containing a "Black and White Mask," an item with minor utility. Lily also learns that monsters decompose into nutrients unless harvested as materials, and that floor bosses respawn over time. She also reflects on the harsh rules of adventurer guilds regarding license renewals and the potential inheritance of lost party members' assets.