"Mamotte Shugogetten" centers around Shichiri Tasuke, a high school student who inadvertently becomes the master of a guardian spirit named Shugogetten after discovering a mysterious book in his school library. Shugogetten, a cheerful and loyal spirit, is tasked with protecting Tasuke from various supernatural threats. However, her presence complicates his life as she is prone to misunderstandings and often causes unintended chaos due to her naivety and overzealous nature.

The narrative unfolds as Tasuke navigates his daily life while dealing with the consequences of Shugogetten's actions. Alongside Shugogetten, other guardian spirits and magical beings enter the story, each with their own quirks and motivations. These include Ran, a mischievous and flirtatious spirit, and Suzu, a shy and reserved spirit who harbors feelings for Tasuke. The interactions between these characters create a blend of comedic and dramatic moments, often revolving around themes of friendship, loyalty, and the challenges of balancing the ordinary with the extraordinary.

As the series progresses, Tasuke and his companions face increasingly dangerous adversaries, including malevolent spirits and rival magic users. These conflicts often stem from the misuse of magical artifacts or the ambitions of those seeking to exploit the power of the guardian spirits. Despite the escalating threats, the core of the story remains grounded in the relationships between the characters, particularly the evolving bond between Tasuke and Shugogetten.

The plot is episodic in nature, with each episode presenting a new challenge or dilemma for the characters to overcome. However, underlying arcs tie these episodes together, gradually revealing more about the origins of the guardian spirits and the true purpose of the magical book that brought them into Tasuke's life. The series balances lighthearted humor with moments of tension and emotional depth, creating a narrative that appeals to a wide audience.