  The niche graph of a digraph $D$ has $V(D)$ as the vertex set and an edge
$uv$ if and only if $(u,w) \in A(D)$ and $(v,w) \in A(D)$, or $(w,u) \in A(D)$
and $(w,v) \in A(D)$ for some $w \in V(D)$. The notion of niche graph was
introduced by Cable et al. (1989) as a variant of competition graph. If a graph
is the niche graph of a digraph $D$, it is said to be niche-realizable through
$D$. If a graph $G$ is niche-realizable through a $k$-partite tournament for an
integer $k \ge 2$, then we say that the pair $(G, k)$ is niche-realizable.
Bowser et al. (1999) studied the graphs that are niche-realizable through a
tournament and Eoh et al. (2018) studied niche-realizable pairs $(G, k)$ for
$k=2$. In this paper, we study niche-realizable pairs $(G, k)$ when $G$ is a
graph and $k$ is an integer at least $3$ to extend their work. We show that the
niche graph of a $k$-partite tournament has at most three components if $k \ge
3$ and is connected if $k \ge 4$. Then we find all the niche-realizable pairs
$(G, k)$ when $G$ is a disconnected graph, when $G$ is a complete graph, and
when $G$ is a connected triangle-free graph.
