The anime "Oh! My Sex Goddess" centers around Keiichi Morisato, a young engineering student and member of his college's motor club. His life takes an unexpected turn when he accidentally summons Belldandy, a beautiful and benevolent goddess from the heavens. Belldandy is part of a system where goddesses assist humans in need, and her arrival is tied to Keiichi's wish for someone to stay by his side forever. Bound by divine rules, Belldandy must remain with Keiichi until her task is complete, leading to a series of comedic, heartfelt, and occasionally chaotic events.

As the story progresses, Keiichi and Belldandy navigate their growing bond while facing challenges from both the human and divine worlds. Belldandy's presence attracts the attention of other supernatural beings, including her sisters Urd and Skuld, who bring their own quirks and complications. Urd, a half-goddess and half-demon, often stirs trouble with her mischievous nature, while Skuld, a younger and more technologically inclined goddess, struggles with her immaturity and jealousy. Together, the trio of goddesses disrupt Keiichi's ordinary life, introducing elements of magic, technology, and divine intervention.

The narrative explores themes of love, loyalty, and the clash between the mundane and the extraordinary. Keiichi's relationships with the goddesses deepen, particularly with Belldandy, as they face obstacles such as divine trials, rivalries, and the complexities of human emotions. The series balances humor with moments of introspection, often highlighting the contrast between Belldandy's serene, otherworldly demeanor and the chaotic energy of those around her. Through its episodic structure, the anime delves into the dynamics of its central characters while maintaining a lighthearted and whimsical tone.