  In this study, we investigate the X-ray properties of WISE
J090924.01+000211.1 (WISEJ0909+0002), an extremely luminous infrared (IR)
galaxy (ELIRG) at $z_{\rm spec}$= 1.871 in the eROSITA final equatorial depth
survey (eFEDS). WISEJ0909+0002 is a WISE 22 $\mu$m source, located in the
GAMA-09 field, detected by eROSITA during the performance and verification
phase. The corresponding optical spectrum indicates that this object is a
type-1 active galactic nucleus (AGN). Observations from eROSITA combined with
Chandra and XMM-Newton archival data indicate a very luminous ($L$ (2--10 keV)
= ($2.1 \pm 0.2) \times 10^{45}$ erg s$^{-1}$) unobscured AGN with a power-law
photon index of $\Gamma$ = 1.73$_{-0.15}^{+0.16}$, and an absorption hydrogen
column density of $\log\,(N_{\rm H}/{\rm cm}^{-2}) < 21.0$. The IR luminosity
was estimated to be $L_{\rm IR}$ = (1.79 $\pm$ 0.09) $\times 10^{14}\,
L_{\odot}$ from spectral energy distribution modeling based on 22 photometric
data (X-ray to far-IR) with X-CIGALE, which confirmed that WISEJ0909+0002 is an
ELIRG. A remarkably high $L_{\rm IR}$ despite very low $N_{\rm H}$ would
indicate that we are witnessing a short-lived phase in which hydrogen gas along
the line of sight is blown outwards, whereas warm and hot dust heated by AGNs
still exist. As a consequence of eROSITA all-sky survey,
$6.8_{-5.6}^{+16}\times 10^2$ such X-ray bright ELIRGs are expected to be
discovered in the entire extragalactic sky ($|b| > 10^\circ$). This can
potentially be the key population to constrain the bright-end of IR luminosity
functions.
