"Kemeko DX!" is a 12-episode anime series that blends comedy, romance, and science fiction. The story centers around Sanpeita Kobayashi, an ordinary high school student whose life takes a bizarre turn when a mysterious girl named M.M. arrives at his doorstep. M.M. is accompanied by a large, robotic suit named Kemeko, which she claims is Sanpeita's fiancée. The series quickly establishes a chaotic dynamic as Kemeko, despite its mechanical appearance, exhibits a fiercely protective and possessive attitude toward Sanpeita, often causing destruction in its attempts to "defend" him.

As the narrative progresses, it is revealed that M.M. and Kemeko are connected to a secretive organization known as the Nishiyama Lab, which is involved in advanced robotics and artificial intelligence. The lab's experiments have led to the creation of Kemeko, a highly advanced robot with a unique personality. M.M., who is actually a young scientist from the lab, is tasked with overseeing Kemeko and ensuring its integration into Sanpeita's life. However, her presence complicates matters further, as she develops her own feelings for Sanpeita, creating a love triangle of sorts.

The series introduces additional characters who contribute to the comedic and dramatic tension. Izumi Kobayashi, Sanpeita's younger sister, is skeptical of M.M. and Kemeko, often clashing with them. Meanwhile, other students at Sanpeita's school, such as the cheerful and energetic Ryoko and the stoic Aki, become entangled in the chaos caused by Kemeko's antics. The interactions between these characters drive much of the humor and emotional moments in the series.

Throughout the episodes, the plot explores themes of identity, relationships, and the ethical implications of advanced technology. Kemeko's existence raises questions about the nature of artificial intelligence and its capacity for emotions, particularly as it becomes clear that Kemeko's feelings for Sanpeita are genuine. The series balances its comedic elements with moments of introspection, particularly as Sanpeita grapples with his feelings toward both M.M. and Kemeko.

The climax of the series involves a confrontation with the Nishiyama Lab, as their true intentions regarding Kemeko and Sanpeita are revealed. This leads to a resolution that ties together the various character arcs and relationships, providing closure to the central conflicts. "Kemeko DX!" concludes with a mix of humor and heartfelt moments, leaving the characters in a place of growth and understanding.