Luna, second princess of the Kingdom of Rimzbel, wields her sword with unmatched skill, embracing a tomboyish spirit that clashes with royal expectations. When the Danbas Empire invades her homeland, she descends into the castle’s depths to awaken Varga, an ancient demon beast bound to her bloodline, in a desperate gambit to turn the tide.

The ritual fuses her body with Varga’s, embedding her into the creature’s head as its living core—a symbiosis that grants dominion over its colossal might but leaves her mortified by the grotesque union. In human form, a reptilian tail curls from beneath her skirt, an ever-present mark of their bond. Harnessing Varga’s power, she obliterates the invaders, only to face a new crisis when her younger sister is abducted by Danbas agents.

Her rescue mission pits her against relentless foes like Bat Robis, a tenacious Danbas general, and uneasy alliances with figures such as Gilbert, a pompous mage. As battles rage, Luna’s drive evolves from defending her realm to severing the cursed fusion. She pursues Zasham, a legendary sorcerer rumored to reverse the binding.

Her journey balances battlefield prowess with the absurdities of her condition—from managing a kaiju-sized companion’s logistics to weathering humiliating fan service incidents. The fusion unravels darker truths about Varga’s imprisonment and ancient evils that threaten the world. Yet amid the chaos, Luna remains anchored by her resolve to shield her family and reclaim a semblance of ordinary life, navigating external trials more than internal metamorphosis.