Kei and Yuri initially served as junior auxiliary agents for the Worlds Works and Welfare Agency (W.W.W.A., abbreviated 3WA) before being assigned together under the code name 'Lovely Angels.' Kei had just finished her fourth probation for a prior offense, while Yuri"s romantic escapades were widely known; moreover, the pair instantly disliked one another upon their first encounter.
At first they resisted collaborating, and Kei even tendered her resignation from the 3WA. Eventually they continued to work side by side, earning the moniker 'the Dirty Pair' because of the unintended collateral damage they frequently inflicted while resolving cases. Their dynamic often leads to chaotic outcomes, but their complementary skills keep missions on track. Even now that they cooperate, they still quarrel and vent grievances at each other.
Despite the frequent clashes, their mutual respect grows over time, cementing their reputation. While many claim these are youthful iterations of the original Lovely Angels Kei and Yuri, this series actually presents an alternate‑universe version of Dirty Pair set between 2248 and 2249.