  Medium-spin excited states of the neutron-rich nucleus $^{87}$Br were
observed and studied for the first time. They were populated in fission of
$^{235}$U induced by the cold-neutron beam of the PF1B facility of the Institut
Laue-Langevin, Grenoble. The measurement of $\gamma$ radiation following
fission has been performed using the EXILL array of Ge detectors. The observed
level scheme was compared with results of large valence space shell model
calculations. The medium-spin level scheme consists of three band-like
structures, which can be understood as bands built on the ${\pi}f_{5/2}$,
${\pi}(p_{3/2}+f_{5/2})$ and ${\pi}g_{9/2}$ configurations. The behavior of the
observed ${\pi}g_{9/2}$ band at high spins shows a considerable deviation from
the shell model predictions. This deviation in this band is probably the result
of an increased collectivity, which can be understood assuming that the
${\pi}g_{9/2}$ high-$\it j$ proton polarizes the core.
