"Ushiro no Hyakutarō" is a supernatural comedy anime centered around the life of a high school student named Hyakutarō, who becomes the host of a mischievous ghost named Ushiro no Hyakutarō. The ghost, invisible to everyone except Hyakutarō, has a penchant for causing trouble and often manipulates situations to create chaos. Despite his antics, Ushiro no Hyakutarō occasionally helps Hyakutarō navigate social challenges and personal dilemmas, forming an unlikely partnership.

The narrative unfolds in a school setting, where Hyakutarō struggles with his ordinary life, often overshadowed by the ghost's unpredictable behavior. Ushiro no Hyakutarō's presence leads to a series of comedic and surreal events, blending supernatural elements with everyday school life. The ghost's interference ranges from harmless pranks to more significant disruptions, affecting Hyakutarō's relationships with classmates, teachers, and even strangers.

Key characters include Hyakutarō, a somewhat timid and average student who finds himself constantly at the mercy of the ghost's whims. Ushiro no Hyakutarō, the titular ghost, is portrayed as a trickster with a mysterious past, often providing cryptic commentary on human behavior. Other characters include Hyakutarō's classmates, who remain oblivious to the ghost's existence but are frequently drawn into the chaos he creates. The interactions between Hyakutarō and Ushiro no Hyakutarō drive much of the humor and tension, as the ghost's actions force Hyakutarō to confront his insecurities and grow as a person.

The series balances episodic humor with moments of introspection, exploring themes of friendship, self-discovery, and the absurdity of human interactions. While the ghost's antics are often the focal point, the story occasionally delves into more serious topics, such as loneliness and the desire for connection, adding depth to the otherwise lighthearted tone. The dynamic between Hyakutarō and Ushiro no Hyakutarō serves as the core of the narrative, blending comedy with subtle emotional undertones.