S.D. Codified Laws § 56-1-7

A promise to answer for the obligation of another is deemed an original obligation of the promiser and need not be in writing where the promise, being for an antecedent obligation of another, is made upon the consideration that the party receiving it cancels the antecedent obligation, accepting the new promise as a substitute therefor; or upon the consideration that a party receiving it releases the property of another from a levy or his person from imprisonment under an execution on a judgment obtained upon the antecedent obligation; or upon a consideration beneficial to the promiser, whether moving from either party to the antecedent obligation, or from another person.