The story begins with Tail, a Beast Tamer and member of the S-rank party "Gale and Phoenix," being unceremoniously fired by his leader, Magnus Rain, a skilled Ice Mage and Swordmaster. The other party members, including the brute force warrior Lyza Brandle and the versatile mage Sylvie Guim, agree with the dismissal, citing Tail and his monster companion, Pipi, as dead weight. Noel Splide, a healer and childhood friend of Tail, offers a tearful apology, confirming his isolation. Tail is devastated, reflecting on the four years since the party's formation.
"Gale and Phoenix" was founded with the ambition of becoming renowned heroes, with Magnus as the "hidden dragon" and the younger members as "phoenix chicks." Tail, a Beast Tamer who could only contract one monster, had been given a phoenix egg by Magnus. He bonded with the hatchling, Pipi, who was expected to grow into a powerful phoenix. However, Pipi remained a chick, and despite Tail's efforts to compensate for Pipi's lack of growth by handling all the party's chores and scouting, he was deemed insufficient.
Magnus offers Tail a cruel ultimatum: break his contract with Pipi and contract a new, useful monster, or be expelled. Tail refuses, unwilling to sacrifice his loyal companion, and is officially cast out. He leaves the inn with Pipi, taking the meager supplies provided by the party, which he views as discarded items. He shares a brief, poignant glance with Noel through the inn window before departing the city for the wilderness.
In the wilderness, Tail and Pipi find shelter in a cave. Tail, a jack-of-all-trades due to his experience in various roles within the party, possesses a range of low-level skills, including scouting and basic magic. He checks their supplies, which are minimal but sufficient for now. He discovers a peculiar monocle, a magical artifact from an ancient ruin that Magnus had given him due to its unknown function.
The next morning, Tail and Pipi head towards the capital city of Neftal. Tail prefers the city's atmosphere of freedom and equality and wishes to remain there, believing the party's constant travels for demon-slaying quests will keep them away. Upon reaching the city gates, the guards, recognizing Tail, greet him with thinly veiled sarcasm and condescension, reflecting his public image as a "burden Tamer" and "eternal chick" who relies on Noel's saintly status. Tail, unfazed, states his intention to register as a solo adventurer.
At the Adventurer's Guild, the Guild Master, clearly biased against Tail, quickly downgrades his rank from the implied S-rank status he held within the party to D-rank, a significant demotion. Tail accepts this, no longer seeking external validation after his expulsion. He chooses a D-rank goblin extermination quest, prioritizing caution.
While searching for the goblins, Tail is confronted by a group of boastful adventurers who mock his demotion. Before a fight can break out, a strong, red-haired girl named Renka Zenland intervenes, effortlessly subduing the aggressors. Renka reveals herself to be a B-rank solo adventurer, known as "Flame Wolf," and expresses deep admiration for Tail, claiming he once saved her life.
Renka invites Tail to a tavern to thank him. There, she reveals she is the daughter of Duke Zangaland, whom Tail's party had rescued from a demonic curse two years prior. Renka, inspired by Tail, became an adventurer herself. She proposes they form a party, but Tail, still hurt by his expulsion and distrustful, declines, stating he needs time alone. Renka, however, secretly decides to follow him, convinced of his hidden strength.
Tail and Pipi proceed to the goblin cave. They find it strangely devoid of goblins, with signs of a violent struggle and a trail of blue blood leading deeper into the cave. They discover the goblins have been annihilated by a powerful entity. Tail identifies the culprit as a Blood Ant, a dangerous, extinction-designated species. As they prepare to report this to the Guild, Renka, who had been following them, is revealed.
Renka, having witnessed Tail's power firsthand, is convinced he is the true core of "Gale and Phoenix." She witnesses Tail's powerful "Rainbow Ray" spell, a unique creation that eradicates a pursuing swarm of Blood Ants, saving her from a Blood Ant Queen. Overwhelmed by his power and their shared past, Renka reiterates her desire to form a party with Tail, which he finally accepts.
Lost in the labyrinthine cave system, Tail and Renka, along with Pipi, find a safe point to rest. Renka uses a valuable "Barrier Stone" to create a protective barrier. Tail discovers that Pipi has been growing by consuming the Blood Ants, a revelation that excites him as it confirms Pipi's potential to become a phoenix. Renka, using a rare "Monocle of Scrutiny," confirms Pipi is an S-rank young phoenix. Tail's own stats have also improved, and he discovers a new, unknown skill: "Survival of the Fittest." Their respite is shattered by the appearance of a Blood Ant Queen, emerging from a cocoon, signaling a new, formidable threat.
