Asteion

Asteion (アスティオン) is a Device created by the Yagami family for Einhard Stratos in ViVid.

Etymology
Asteion (αστειον) means "refined" in. The manga reveals that it was the name of an unborn baby of two s that belonged to Claus Ingvalt, Einhard's ancestor, and whom Olivie Sägebrecht liked a lot.

Einhard has nicknamed her Device "Tio".

Appearances
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.

Forms
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.

As commented by Dieci, Asteion is skillful in damage mitigation and recovery assistance.