Let $G=(V,E)$ be a finite, simple, undirected graph. Let $D_2(G)$ be the graph with vertex set $V$, and two vertices form an edge if and only if they have distance $2$ in the original graph $G$.

Note that, if $C_{2k+1}$ is the circle on $2k+1$ points for an integer $k\geq 2$, we have $C_{2k+1}\cong D_2(C_{2k+1})$.

**Question.** Is there a connected, non-regular graph $G=(V,E)$ with $|V|>2$ such that $G\cong D_2(G)$?