|This article uses material from the Asteion article on the Nanoha wiki at Wikia and is licensed under the Creative Commons Attribution-Share Alike License.|
Asteion (αστειον) means "refined" in Greek. The manga reveals that it was the name of an unborn baby of two snow leopards that belonged to Claus Ingvalt, Einhard's ancestor, and whom Olivie Sägebrecht liked a lot.
Einhard has nicknamed her Device "Tio".
Asteion makes its first appearance in the house of the Yagami family. Its outer coating, designed by Agito, resembles a plush snow leopard, honoring the snow leopards of Shutra that were bred as soldiers and fighters by Claus' family.
Like Sacred Heart, Asteion does not change its form when activated. Upon its first setup, it changed the hairstyle of the adult-mode Einhard. It may be absorbed into Einhard's body after an Adult Mode setup, probably to perform better auxiliary control.