In line with the framework of Theory of Interaction proposed by Yuxi Fu, we formalize the asynchronous theory in model independent way. Borrowing the idea from Church-Turing Thesis, we introduce ℂ-calculus as a minimal interaction model. We give model independent characterization for asynchronous bisimulation equivalence which is generalized to subbisimilarity used as the criteria for Interaction Completeness of interaction models. We present an encoding from ℂ-calculus to asynchronous π-calculus and prove that it satisfies the subbisimilarity statements.