"City Hunter: The Secret Service" is a two-episode OVA that serves as a spin-off of the popular "City Hunter" franchise. The narrative centers on Ryo Saeba, a skilled private detective and marksman known as the "City Hunter," who operates in Tokyo. Ryo is hired to protect Princess Lilia, the heir to the fictional European kingdom of Sildavia, during her visit to Japan. The assignment is complicated by the presence of a terrorist organization determined to assassinate Lilia to destabilize her country.

Ryo’s mission intertwines with his usual comedic and flirtatious demeanor, often clashing with his professional responsibilities. His partner, Kaori Makimura, assists him, providing both emotional support and a grounding presence to counterbalance Ryo’s antics. The story unfolds as Ryo uncovers a conspiracy involving high-ranking officials and international intrigue, forcing him to rely on his sharp instincts, combat skills, and marksmanship to protect Lilia and thwart the terrorists.

The OVA maintains the franchise’s signature blend of action, humor, and lighthearted moments, while also exploring themes of loyalty, duty, and the complexities of political power. Ryo’s character remains consistent with his established persona—charismatic, resourceful, and occasionally reckless—while the narrative introduces new dynamics through Lilia’s character, who adds a layer of tension and vulnerability to the plot. The series balances its episodic structure with a self-contained story, making it accessible to both longtime fans and newcomers to the "City Hunter" universe.