  We study the properties of a quantum impurity embedded in a superconducting
host of a d-wave symmetry. The superconductor is described by the extended
negative $U$
  Hubbard model while the impurity introduces a repulsive interaction to the
system around the central site. We discuss the influence of this repulsion on
the local properties
  (density of states, electron pairing and spontaneous current around the
impurity) of the superconductor. We show the condition of $\pi$ - like
behaviour, defined as two subsystems having a phase difference of $\pi$, in the
system by using a proper combination of attractive pairing bond interaction and
repulsive one between electrons located at the impurity and nearest neighbour
sites.
