While there is slight differences in the Lovely Angels history throughout the continuities in the Dirty Pair franchise, the most commonly used history the angels have is that both Kei and Yuri met each other 4 years before they both graduated from planet Mezuiru academy and became a team together when they joined the 3WA right after. In the Dirty Pair Flash continuity, it is shown that the team code name is passed down as Kei and Yuri weren't the original members but Iris and Molly were.