  The $\gamma$-ray narrow-line Seyfert 1 (NLS1) galaxies can be considered to
be the third class of $\gamma$-ray active galactic nuclei possessing
relativistic jets. In this paper, we present multi-band high resolution Very
Long Baseline Array (VLBA) images of the $\gamma$-ray NLS1, SDSS
J211852.96$-$073227.5 (J2118$-$0732, $z=0.26$). We find a core-jet radio
morphology and significant flux density variations in the radio core. The high
brightness temperature estimated from VLBA images and core variability
demonstrate that it exhibits substantial relativistic beaming effects. From
considering radio emission in several bands, we find that the source has an
inverted spectrum above 1 GHz but a steep spectrum at low frequencies from 74
MHz to 1 GHz; these may arise from the present activity and the old
diffuse/extended emission, respectively. The core-jet morphology, significant
flux density variations, and beaming effect make J2118$-$0732 resemble a
blazar. Considering the low mass of its central black hole and ongoing merger
environment, J2118$-$0732 may represent a low-mass, low-power counterpart of
blazars, and may finally evolve to a blazar.
