  It is known that for any knot $K$ every (meridionally) trace-free
$SL_2(C)$-representation of the knot group $G(K)$ gives an
$SL_2(C)$-representation of the fundamental group $\pi_1(\Sigma_2K)$ of the
2-fold branched covering $\Sigma_2K$ of the 3-sphere branched along $K$. In
this paper, we show by using a notion called a ghost character of a knot that
for the (4,5)-torus knot $T_{4,5}$ the fundamental group
$\pi_1(\Sigma_2T_{4,5})$ has an $SL(2,C)$-representation which cannot be given
by any trace-free $SL_2(C)$-representation of $G(T_{4,5})$.
