"He Is My Master" centers around the eccentric and wealthy teenager Yoshitaka Nakabayashi, who unexpectedly inherits a vast fortune and a luxurious mansion after his parents pass away. With his newfound wealth, Yoshitaka decides to live a life of indulgence and hires two sisters, Izumi and Mitsuki Sawatari, as his maids. The sisters, having lost their parents and facing financial difficulties, reluctantly accept the job despite Yoshitaka's bizarre and often inappropriate demands.

Izumi, the older sister, is practical and responsible, often trying to keep Yoshitaka's outlandish behavior in check while navigating her new role. Mitsuki, the younger sister, is more naive and cheerful, often oblivious to the more troubling aspects of their employer's antics. The dynamic between the three characters forms the core of the series, with Yoshitaka frequently testing the limits of their patience through his selfish and eccentric requests.

The narrative explores the comedic and sometimes awkward situations that arise from the mismatched trio living together. Yoshitaka's obsession with creating a "perfect maid experience" leads to numerous over-the-top scenarios, including elaborate costumes, strange household rules, and his attempts to impose his will on the sisters. Despite his flaws, Yoshitaka occasionally shows moments of vulnerability, hinting at deeper insecurities beneath his brash exterior.

Additional characters, such as Yoshitaka's childhood friend Anna and the family lawyer, add further layers to the story, often serving as foils or catalysts for the central trio's interactions. The series balances humor with occasional moments of sincerity, as the characters gradually develop a sense of camaraderie despite their differences. The episodic structure allows for a variety of comedic situations, ranging from slapstick to situational humor, while maintaining a lighthearted tone throughout.