  Large-scale outflows are generally considered as a possible evidence that
active galactic nuclei (AGNs) can severely affect their host galaxies. Recently
an ultraluminous IR galaxy (ULIRG) at $z=0.49$, AKARI J0916248+073034, was
found to have a galaxy-scale [OIII] $\lambda$5007 outflow with one of the
highest energy-ejection rates at $z<1.6$. However, the central AGN activity
estimated from its torus mid-IR (MIR) radiation is weak relative to the
luminous [OIII] emission. In this work we report the first NuSTAR hard X-ray
follow-up of this ULIRG to constrain its current AGN luminosity. The intrinsic
2-10 keV luminosity shows a 90% upper-limit of $3.0\times10^{43}$ erg s$^{-1}$
assuming Compton-thick obscuration ($N_{\rm H}=1.5\times10^{24}$ cm$^{-2}$),
which is only 3.6% of the luminosity expected from the extinction corrected
[OIII] luminosity. With the NuSTAR observation, we succeed to identify that
this ULIRG has a most extreme case of X-ray deficit among local ULIRGs. A
possible scenario to explain the drastic declining in both of the corona
(X-ray) and torus (MIR) is that the primary radiation from the AGN accretion
disk is currently in a fading status, as a consequence of a powerful nuclear
wind suggested by its powerful ionized outflow in the galaxy scale.
