Takayoshi Sasaki has been working on the synthesis and characterizations of a variety of layered host compounds. His particular interest has been directed to soft-chemical synthesis utilizing their chemical reactions, e. g., intercalation. He is one of pioneers for investigation on delamination since he found that a layered titanate undergoes total exfoliation into colloidal single layers for the first time. Since then, he succeeded in synthesizing a number of functional oxide and hydroxide nanosheets such as MnO2, Cs4W11O36, and Co(OH)2. He has demonstrated that these nanosheets show novel physicochemical properties associated with the extremely high 2D anisotropy having a molecular thickness. One of the highlights in the course of such study is the discovery of superconductivity in 2D CoO2 sheets, which is a very hot topic in recent years.