Herein, we report an anomalous porous molecular crystal built of 'C–H···N-bonded double-layered roof/floor components' and 'wall components of a segregatively interdigitated architecture'.  This complicated porous structure consists of only one type of fully aromatic multi-joint molecule.  Although a C–H···N bond is extremely labile, the porous crystal maintains its porosity until thermal breakdown of the C–H···N bonds at 202 °C to afford a non-porous polymorph.  While this non-porous crystal survives even at 325 °C, it can retrieve the parent porosity under acetonitrile vapor.