"La Blue Girl Returns" is a sequel to the original "La Blue Girl" series, continuing the adventures of Miko Mido, a ninja from the Mido clan. The narrative revolves around the ongoing battle between the Mido clan and the demonic forces led by the evil Kuno. Miko, trained in the ancient art of ninja eroticism, uses her unique abilities to combat these supernatural threats.

The story begins with Miko being summoned to a mysterious island where a new threat has emerged. The island is under the control of a powerful demon named Lord Kuromatsu, who seeks to harness the energy of the island's inhabitants to open a portal to the demon world. Miko's mission is to thwart Kuromatsu's plans and prevent the invasion of the human world by demonic entities.

Throughout the series, Miko encounters various allies and adversaries. Among her allies is her younger sister, Maya, who also possesses ninja skills and aids Miko in her quest. The sisters face numerous challenges, including battles with Kuromatsu's minions and other supernatural creatures. The narrative explores themes of loyalty, family, and the struggle between good and evil.

The plot is driven by a series of intense battles and strategic confrontations, with Miko utilizing her ninja techniques and erotic powers to overcome her enemies. The series also delves into the backstory of the Mido clan, revealing the origins of their unique abilities and their long-standing conflict with demonic forces.

As the story progresses, Miko and Maya uncover deeper layers of the conspiracy involving Kuromatsu and his plans. The climax involves a final showdown between Miko and Kuromatsu, where the fate of both the human and demon worlds hangs in the balance. The resolution of the series ties up the main plotlines while leaving room for potential future developments.

"La Blue Girl Returns" maintains a focus on action and supernatural elements, with a narrative that balances intense combat sequences with moments of character development and exploration of the series' mythos. The main characters, particularly Miko and Maya, are central to the story, with their relationship and individual growth playing key roles in the unfolding events. The series provides a continuation of the themes and conflicts introduced in the original "La Blue Girl," offering a cohesive and engaging narrative for fans of the franchise.