"Dirty Pair OAV 4" continues the adventures of Kei and Yuri, the two Trouble Consultants from the 3WA (World Welfare Work Association), known as the Lovely Angels. The story is set in a futuristic universe where the duo is tasked with resolving crises, though their missions often result in unintended chaos. In this installment, Kei and Yuri are assigned to investigate a mysterious incident on the planet Agerna, where a research facility has been destroyed under suspicious circumstances. The facility was conducting experiments on a powerful energy source, and its destruction threatens to destabilize the planet's ecosystem.

As Kei and Yuri delve deeper into the investigation, they uncover a conspiracy involving corporate espionage, illegal weapons development, and a rogue scientist seeking to weaponize the energy source. The narrative unfolds with a mix of action, humor, and suspense, as the duo navigates through dangerous encounters, including clashes with mercenaries and high-tech security systems. Their dynamic partnership and contrasting personalities—Kei's brash impulsiveness and Yuri's calm pragmatism—drive the story forward, often leading to both comedic and dramatic moments.

The plot thickens as the Lovely Angels discover that the rogue scientist has ties to a powerful corporation with ambitions of galactic domination. The stakes escalate when the energy source is revealed to be unstable, posing a threat not only to Agerna but to the entire star system. Kei and Yuri must race against time to prevent a catastrophic explosion while contending with the scientist's advanced technology and the corporation's relentless pursuit. The story concludes with a high-stakes showdown, showcasing the duo's resourcefulness and teamwork as they manage to avert disaster, albeit with their signature flair for collateral damage. The narrative maintains a balance between its sci-fi elements and character-driven moments, solidifying the Dirty Pair's reputation as both effective agents and chaotic forces of nature.