Distinctive red gem from Part 2 of Jojo no Kimyou na Bouken. Sought after by the Pillar Men, as it is key in their quest for perfection. Often seen as a necklace on Lisa Lisa.
Given Hirohiko Araki's fondness for musical references, it is not unlikely that the object might be named for either the album Aja, Steely Dan's sixth, released on 23 September 1977, and the song "Aja" on said album.
