"Getsumen to Heiki Mina" is a 12-episode anime series that blends elements of science fiction, comedy, and romance. The story centers around Mina Tsukishiro, a seemingly ordinary high school girl who harbors a secret identity as a lunar warrior sent to Earth to protect it from alien invaders. These invaders, known as the Menool, are a race of extraterrestrial beings intent on conquering Earth by exploiting its resources and manipulating its inhabitants.

Mina’s mission is to infiltrate human society and gather intelligence while defending the planet from the Menool’s schemes. To maintain her cover, she enrolls in a high school and befriends her classmates, including the kind-hearted but oblivious Kengo Mano, who becomes a central figure in her life. Despite her extraordinary abilities and advanced technology, Mina struggles to balance her duties as a warrior with the challenges of everyday teenage life, including schoolwork, friendships, and her growing feelings for Kengo.

The Menool employ various tactics to achieve their goals, often disguising themselves as humans or using mind control to manipulate others. Mina must confront these threats while keeping her true identity hidden, leading to a series of comedic and action-packed encounters. Her battles against the Menool are marked by her use of a unique weapon, the "Getsumen To Heiki," a crescent-shaped blade that symbolizes her lunar origins.

As the series progresses, Mina’s relationships with her classmates deepen, particularly her bond with Kengo, who remains unaware of her true nature. This dynamic creates tension as Mina grapples with the ethical implications of her mission and the potential consequences of revealing her identity. The narrative explores themes of loyalty, identity, and the clash between duty and personal desires, all while maintaining a lighthearted tone through its comedic elements.

The supporting cast includes Mina’s classmates, such as the energetic and curious Chiyuri Tamagawa, who often unwittingly complicates Mina’s efforts to maintain her cover. The Menool are represented by various antagonists, each with distinct personalities and strategies, adding variety to the conflicts Mina faces. The series concludes with a resolution that ties together the central plotlines while leaving room for interpretation regarding Mina’s future on Earth.

"Getsumen to Heiki Mina" combines action, humor, and romance to create a narrative that balances its sci-fi premise with relatable human experiences. The series’ exploration of Mina’s dual life as both a warrior and a high school student forms the core of its appeal, offering a unique take on the alien-invasion genre.