Teramin manifests as a cat-like entity sculpted from luminous green gemstone, distinguished by Egyptian-styled eye motifs and a tail culminating in a glowing point. This being perpetually levitates, never touching the ground, and adorns a golden neckpiece. Its speech patterns consistently incorporate the suffix "min" as a linguistic signature.

Narratively, Teramin partners with Lime Ashiya to fuse into the Yo-kai Hero identity Ashura Gilfer. It wields the specialized power to generate Onryo entities from inanimate objects, though only under specific conditions—exemplified when transforming a tank into Buruburooro in episode YG054.

Within the mobile game *Yo-kai Watch: Wibble Wobble*, Teramin featured exclusively in a limited-time event (March 16-31, 2021), obtainable solely via temporary Crank-a-kai mechanisms. Gameplay attributes included level-dependent statistics (HP: 398-702, Attack: 546-963 at level 50), the "Minmin Beam" Soultimate move erasing central Wib Wob alignments, event-exclusive combat enhancements amplifying ally damage while reducing opponent damage, and a skill accelerating Soultimate recharge upon +4 Wib Wob activation.

The character’s name derives from "Terra," reflecting earthly connections. Its inaugural anime appearance occurs in episode YG053 of the series.