  Using the high resolution Milky Way-like model from Auriga simulation we
study the chemical properties of the Galactic bulge, focusing on the
metallicity difference between stars on the near side (in front of the Galactic
center) and the far side (behind the Galactic center). In general, along
certain sight lines the near side is more metal-rich than the far side,
consistent with the negative vertical metallicity gradient of the disk, since
the far side is located higher above the disk plane than the near side.
However, at the region $l<0^\circ$ and $|b|\le6^\circ$, the near side is even
more metal-poor than the far side, and their difference changes with the
Galactic longitude. This is mainly due to the fact that stars around the minor
axis of the bar are more metal-poor than those around the major axis. Since the
bar is tilted, in the negative longitude region, the near side is mainly
contributed by stars close to the minor axis region than the far side to result
in such metallicity difference. We extract stars in the X-shape structure by
identifying the overdensities in the near and far sides. Their metallicity
properties are consistent with the results of the whole Galactic bulge. The
boxy/peanut-shaped bulge can naturally explain the metallicity difference of
the double red clump stars in observation. There is no need to involve a
classical bulge component with different stellar populations.
