Fuyōheki

The Fuyōheki is a magical item from the InuYasha manga series.

Originally in the possession of Gakusanjin, it is a stone that masks the presence of yōki (yōkai energy).

Circa #335 it was stolen by Naraku or his agents (possibly Hakudōshi). The Fuyōheki was then given by Naraku himself to Akago in order to mask him (and Naraku's heart inside him) completely from Naraku's enemies. It was later absorbed (along with Akago himself) by Mōryōmaru.