"Tonari no Yōkai-san" is a slice-of-life anime that explores the coexistence of humans and yōkai (supernatural creatures) in a modern setting. The narrative unfolds in a small, peaceful town where humans and yōkai live side by side, often interacting in ways that blur the lines between the mundane and the mystical. The story centers on the daily lives of various characters, both human and yōkai, as they navigate their relationships, challenges, and the occasional supernatural occurrence.

The main characters include a human bookstore owner who has a deep fascination with yōkai and often finds himself mediating between the two worlds. His interactions with yōkai are marked by curiosity and respect, and he serves as a bridge between the human and supernatural communities. Another key figure is a young yōkai girl who is still learning about her powers and the human world. Her innocence and eagerness to understand human customs provide a heartwarming perspective on the blending of cultures.

Other notable characters include a wise, elderly yōkai who acts as a mentor to younger yōkai, offering guidance and wisdom drawn from centuries of experience. There is also a mischievous yōkai who enjoys playing harmless pranks on humans, often leading to humorous situations. The human residents of the town, including a schoolteacher and a local shopkeeper, are portrayed with their own unique quirks and personalities, adding depth to the community dynamic.

The plot is episodic, with each episode focusing on a different aspect of life in the town. Themes of friendship, understanding, and coexistence are prevalent, as the series highlights the importance of mutual respect and empathy between humans and yōkai. While the tone is generally lighthearted, there are moments of introspection and emotional depth, particularly when exploring the challenges faced by yōkai in a world that is increasingly dominated by humans.

The series does not follow a single overarching plot but instead presents a collection of interconnected stories that paint a vivid picture of the town and its inhabitants. These stories range from humorous encounters and everyday mishaps to more poignant tales of loss and reconciliation. Through its diverse cast and varied narrative threads, "Tonari no Yōkai-san" offers a rich tapestry of life in a world where the supernatural is an integral part of the everyday.