Katsuhiko Ariga has been working on supramolecular chemistry especially related with self-assembly processes, ultrathin films and molecular recognitions. Accomplishments in his researches contribute significantly developments of biomemetic systems as well as physicochemical understanding on interfacial phenomena. Especially, pioneer researches of layer-layer supramolecular assembly have been highly evaluated, and he is also recognized as an authority of supramolecular recognition at the interfaces.