A Lax pair of a lattice equation whose entropy vanishes

In this paper, we present multi parametric quadgraph equations which are consistent around the cube. These equations are obtained by applying a `double twist' to known integrable equations. Furthermore, we perform a limit to one of these equations to derive the non-symmetric equation which is given by Hietarinta and Viallet. As a result, we obtain a novel Lax pair of this equation.