  We report the discovery of two companion sources to a strongly lensed galaxy
SPT0418-47 ("ring") at redshift 4.225, targeted by the JWST Early Release
Science program. We confirm that these sources are at a similar redshift as the
ring based on H$\alpha$ detected in the NIRSpec spectrum, and [C II] 158 $\mu$m
line from ALMA. Using multiple spectral lines detected in JWST/NIRSpec, the
rest-frame optical to infrared images from NIRCam and MIRI, and far-infrared
(FIR) dust continuum detected by ALMA, we argue that the newly discovered
sources are actually lensed images of the same companion galaxy, hereafter
referred to as SPT0418-SE ("SE"), located within 5 kpc in the source plane of
the ring. The star formation rate derived using [C II] and dust continuum puts
a lower limit of 17 M$_\odot$/yr, while the SFR$_\mathrm{H\alpha}$ is estimated
to be >2 times lower, thereby confirming that SE is a heavily dust obscured
star-forming galaxy. Analysis using optical strong line diagnostics suggests
that SE has near solar elemental abundance, while the ring appears to have
super-solar metallicity O/H and N/O. We attempt to reconcile the high
metallicity in this system by invoking early onset of star formation with
continuous high star forming efficiency, or that optical strong line
diagnostics need revision at high redshift. We suggest that SPT0418-47 resides
in a massive dark matter halo with yet to be discovered neighbors. This work
highlights the importance of joint analysis of JWST and ALMA data for a deep
and complete picture of the early Universe.
