(Trifluoromethyl)sulfonyl group (Tf=CF₃SO₂) is one of the strongest electron-withdrawing substituents. A number of strongly acidic compounds bearing this substituent such as TfOH and Tf₂NH have been reported. During a past decade, structurally similar carbon(C-H)acids “Tf₂CHR” have attracted much attention as a new class of superacidic molecules, which show stronger acidity than sulfuric acid molecule, owning to excellent performance as acid catalysts in organic synthesis. Needless to say, development of such novel acids implies creation of highly stable anionic species as well. In recent years, the authors have been engaged in chemical research focusing on highly stabilised carbanions [Tf₂CR]^-. Here, the carbanion moiety is effectively stabilised by two Tf groups through electron-withdrawing inductive effect and negative hyperconjugation. Our effort revealed chemically inert, less coordinating, and lipophilic properties of this anion. In this account, we describe our achievements in the [Tf₂CR]^- chemistry including synthesis, structure, reactivity, and functions.