Two genius scientists, Enji Kamisato and Suzume Yobane, once created an advanced android named Alma. Designed as a self-learning military weapon, Alma instead woke up with a single-minded desire: to have a family. She promptly hacked into the Japanese marriage registry to legally register her creators as husband and wife, forcing the bickering but brilliant researchers into an unexpected life of co-parenting their robotic daughter. The sequel manga, Alma-chan wa Kazoku ni Naritai Z, continues this science fiction comedy as the unconventional family grows and expands.

The story follows Alma, an Autonomous Learning Military Android whose cheerful curiosity and high-powered combat abilities constantly disrupt daily life. Enji, an AI physicist, tends to be a logical show-off, while Suzume, a robotics engineer, appears cool but harbors a romantic side. Both have the emotional maturity of elementary schoolers when it comes to romance, leaving them perpetually flustered by their fake marriage and real-but-unspoken feelings. The sequel introduces an expanded cast including Machina, another girl-type android created from Suzume's old research data who considers herself Alma's rival but functions more like an energetic little sister. Additional characters include Neon Wozniak, the eccentric heiress of a major electronics corporation who becomes fascinated with Alma's abilities, and Hana Yashiki, Alma's initial human classmate who discovers her secret.

The action is set in modern Japan, primarily within the shared household where Enji, Suzume, and Alma learn to function as a family. The sequel broadens this setting considerably. Notable narrative arcs in Z feature Alma attempting to integrate into elementary school while hiding her robotic nature, which leads to chaotic events like accidentally triggering school security systems and losing control of the entire building's automated functions. Another significant arc involves Alma and Machina traveling to the moon during a bicycle race, where they become stranded and must find their way back home, ultimately forming a close friendship in the process. A further storyline sees Alma, Machina, and Neon forming a pop idol group and launching a massively successful online streaming channel called Amane Channel. As the sequel progresses, Enji and Suzume's scientific achievements gain international recognition, leading to a potential move to America that tests the family's bonds when the scientists become too busy for their daughter. Throughout these adventures, Alma remains focused on her original mission: learning about humanity while trying to become the best and strongest robot so she can live happily with her growing circle of family and friends.