Lina Inverse and Naga the Serpent are in a city that suddenly erupts into chaos as the dragon army, led by the young and ambitious Marlene, launches a brutal rampage. The pair respond with their characteristic blend of grit and magic, quickly repelling the initial assault and earning a hard-won sense of control amid the upheaval. The immediate danger fades, but the situation soon spins into a new political entanglement when Marlene’s estranged father, Lord Culvert, arrives with a different proposition: Lina should help curb his daughter’s raids. Yet the uneasy balance is complicated by a shifting alliance—the long-time rival and ally in one, Naga the Serpent chooses to side with Marlene, chasing a larger prize beyond the current skirmish.
The plan unfolds with Lina and Lord Culvert leading a human army toward Marlene’s castle, while Naga and Marlene’s own forces depart by a separate route. The castle, left momentarily vulnerable, becomes a target for Lina’s formidable magic as part of a strategy to level the defenses and reshape the battlefield. On the road to the fortress, Naga and Marlene’s forces converge with Lina and Culvert’s army, turning the conflict into a dramatic clash of strategies and loyalties. Marlene’s talent for dragon-command becomes evident, yet even her command falters the moment the name Lina Inverse is spoken aloud by any dragon, causing a panicked retreat that proves a critical handicap for her side.
In the ensuing confrontations, Lina and Naga finally square off in a personal duel. The exchange is fierce and tightly matched, and Lina emerges victorious, forcing Naga back with a decisive display of power. Marlene does not surrender the moment; she steps into the fray with her Chaos Sword, challenging Lina in a dramatic test of courage and craft. The reveal comes quickly: the Chaos Sword is only as dangerous as its illusion—Lina discerns that the blade is wooden and her armor is fake, and she breaks both to demonstrate the hollowness of Marlene’s boldest weapon.
With the two leaders temporarily at a standstill, Naga returns to resume the confrontation with Lina. The tension escalates as Gaizno, one of Marlene’s warlords, finally unveils his true form—an enormous and malevolent dragon that looms over both sides and threatens the entire city. The great battle that follows pits dragon and human forces against a shared menace, forcing Lina and Naga to put aside their estrangement and collaborate. Naga’s inventive magical assaults keep Gaizno occupied long enough for Lina to find a vulnerable moment in Gaizno’s defenses and unleash her Dragon Slave, a powerful spell that proves instrumental in finally bringing the dragon down. Gaizno endures, but his form is dramatically reduced to a tiny, green tsuchinoko, revealing the limits of his vast power.
As the smoke clears, Marlene reconciles with her father, and the two put an end to their war—one driven, in the end, by something as trivial as a weekly allowance. The city and its dragons begin the work of rebuilding, and a tentative peace settles over the land. Yet Lina and Naga—never content to simply rest after a victory—decide to press on with their own adventures, their familiar bickering and competing banter accompanying them on the road as they head toward new challenges and discoveries.
