A. Plaintiff 1) lent KRW 670,00,000 to the Defendant on December 30, 201, and KRW 300,000,000,000 to the Defendant on February 27, 2012. On March 15, 2012, the Defendant prepared a loan certificate and promissory note to the Plaintiff that the Plaintiff borrowed KRW 1 billion, including the above loan, from the Plaintiff. On April 17, 2012, the Plaintiff completed the registration of the establishment of a mortgage with the maximum debt amount of KRW 1.2 billion (hereinafter “the instant apartment”). On April 17, 2012, the Plaintiff completed the registration of the establishment of the D Apartment under the above loan debt amount (hereinafter “the instant debt”).

B) On August 12, 2013, the Plaintiff purchased the instant apartment from the Defendant for KRW 1,680,000,000 from the purchase price, and the down payment of KRW 1 billion out of the purchase price is replaced by the instant debt, and the remainder of KRW 680,00,000,000, succeeded to the Defendant’s loan obligation, in lieu of payment. The remainder of KRW 480,000,000 shall be paid on November 5, 2013, and the Defendant agreed to deliver all documents necessary for the registration of transfer of ownership to the said apartment and to cooperate with the Plaintiff (hereinafter “instant sales contract”).

(C) However, on October 2, 2013, the Defendant recovered documents necessary for the registration of transfer of ownership of the instant apartment that was entrusted to a certified judicial scrivener for the implementation of the instant sales contract. On October 4, 2013, the Defendant completed the registration of creation of chonsegwon with the deposit money of KRW 900 million in the future regarding the instant apartment on October 4, 2013, which constitutes a seller’s refusal of performance, and the Plaintiff notified the Defendant of the cancellation of the said sales contract on December 13, 2013 on the ground of the Defendant’s nonperformance. Since the instant sales contract was cancelled due to the foregoing reasons attributable to the Defendant, the Defendant returned the said down payment to the Plaintiff by restitution following the cancellation of the sales contract.