"Onbu Obake" is a supernatural comedy anime that revolves around the daily life of a young boy named Shouta, who encounters a mischievous ghost named Onbu. Onbu, a small, ghostly creature with a playful and sometimes troublesome nature, attaches itself to Shouta's back, becoming an inseparable part of his life. The series explores the humorous and often chaotic situations that arise from their unusual bond.

Shouta, an ordinary elementary school student, initially struggles to cope with Onbu's antics, which range from causing minor disruptions to creating significant challenges in his daily routine. Despite the inconvenience, Shouta gradually forms a unique friendship with Onbu, learning to navigate the complexities of living with a supernatural entity. The narrative delves into their interactions with other characters, including Shouta's family, friends, and various other spirits and humans who become involved in their adventures.

The plot is episodic, with each episode presenting a new scenario or challenge that Shouta and Onbu must face together. These episodes often blend humor with moments of heartfelt connection, highlighting the evolving relationship between the boy and the ghost. The series also incorporates elements of Japanese folklore and mythology, as Onbu's presence introduces Shouta to a hidden world of spirits and supernatural phenomena.

Key characters include Shouta's supportive but often bewildered family, who must adapt to the presence of Onbu in their household. Additionally, other spirits and supernatural beings occasionally appear, adding depth to the world-building and providing further opportunities for comedic and dramatic storytelling. The dynamic between Shouta and Onbu serves as the central focus, with their bond growing stronger as they overcome various obstacles together.

"Onbu Obake" balances lighthearted comedy with themes of friendship, acceptance, and the blending of the human and supernatural worlds. The series maintains a consistent tone of whimsy and charm, making it accessible to a wide audience while offering a fresh take on the classic ghost story trope.