  Based on 14 Miras located in 7 globular clusters, we derived the first
gr-band period-luminosity (PL) at maximum light for the large-amplitude Mira
variables using the multi-year light-curve data collected from the Zwicky
Transient Facility (ZTF). Since Miras are red variables, we applied a
color-term correction to subsets of ZTF light curves, and found that such
corrections do not have a large impact on period determinations. We applied our
derived PL relations to the known extragalactic Miras in five local galaxies
(Sextans, Leo I, Leo II, NGC6822 and IC1613), and determined their Mira-based
distances. We demonstrated that our PL relations can be applied to short-period
(<300 days) Miras, including those in the two most distant galaxies (NGC6822
and IC1613) in our sample even when only a portion of the light-curves around
maximum light have detections. We have also shown that the long-period
extragalactic Miras do not follow the PL relations extrapolated to longer
periods. Hence, our derived PL relations are only applicable to the
short-period Miras, which will be discovered in abundance in local galaxies
within the era of Vera C. Rubin Observatory's Legacy Survey of Space and Time.
