"Shōnen Maid" centers around Chihiro Komiya, a young boy who lives a frugal life with his mother after his father abandoned them. Following his mother's sudden death, Chihiro is left alone and struggles to cope with his loss. His life takes an unexpected turn when he is approached by Madoka Takatori, a wealthy and eccentric man who claims to be his uncle. Madoka reveals that he is Chihiro's maternal uncle and offers to take him in, providing him with a new home at the Takatori estate.

Initially resistant to the idea, Chihiro reluctantly agrees to live with Madoka after realizing he has no other options. Upon arriving at the sprawling Takatori mansion, Chihiro is overwhelmed by its grandeur and the sheer number of staff maintaining the property. However, he quickly notices that the mansion is cluttered and disorganized, despite the staff's efforts. Chihiro, who has inherited his mother's meticulous cleaning habits, begins tidying up the estate, earning the admiration of the staff and Madoka.

Madoka, a carefree and somewhat irresponsible individual, is impressed by Chihiro's diligence and proposes that he become the mansion's "maid" in exchange for room and board. Chihiro, though initially resistant to the idea, agrees, seeing it as a way to contribute and maintain order in his new environment. As he settles into his role, Chihiro forms bonds with the staff and gradually adapts to his new life, finding a sense of purpose and belonging.

Throughout the series, Chihiro's relationship with Madoka evolves as they navigate their newfound family dynamic. Madoka, who initially appears aloof and self-centered, reveals a more caring and supportive side as he helps Chihiro process his grief and adjust to his new circumstances. The series also explores themes of family, responsibility, and personal growth, as Chihiro learns to balance his duties as the mansion's maid with his own emotional needs.

The supporting cast includes the mansion's staff, each with distinct personalities and roles, who contribute to the warmth and humor of the story. Their interactions with Chihiro and Madoka add depth to the narrative, highlighting the importance of community and mutual support. The series balances lighthearted moments with poignant reflections on loss and resilience, creating a heartfelt and engaging story.