Aromatic rings hold a central position in organic chemistry and govern the fundamental nature of numerous aromatic compounds.  Aromatic rings are stable due to their aromatic resonance energy and thus usually considered as being unbreakable.  Compared with exocyclic modifications of aromatic compounds, little is known about endocyclic modifications such as substitutions of endocyclic atoms and atom insertions into the rings through partial disassembly of the cyclic skeletons and subsequent ring reconstruction.  Since 2012, we have been interested in developing a series of new synthetic methods to achieve endocyclic modifications of heteroarenes as a game-changing strategy in organic synthesis. I will talk about our endeavors to establish ‘aromatic metamorphosis’,¹ focusing on the catalytic transformations of heteroaromatic skeletons.²