Yuri is best known as the Leader of the Purple Sky, a title derived from the Tome of the Purple Sky.
In the Mahou Shoujo Lyrical Nanoha universe, Yuri has a complicated history. Originally human and born during the Ancient Belkan era, she was transformed into a sentient combat system called "Unbreakable Dark" (or U-D for short) through a program designed to overwrite the Book of Darkness. This form stuck with her until the events of The Gears of Destiny brought about her separation from the system.
By the time of the INNOCENT storyline, Yuri—now going by Yuri Eberwein—has moved on to a more ordinary life. She's studying abroad in Uminari City alongside her companions Stern, Levi, and Dearche.
Content compiled by AnimeList.moe from publicly available sources.
