A. On December 24, 2015, the Defendant entered into a sales contract with C Co., Ltd. (hereinafter “C”) and Sejong Special Self-Governing City D Apartment E (hereinafter “instant apartment”) with the supply price of KRW 341,00,000,000.

B. The Plaintiff’s purchase of the apartment in this case 1) decided to purchase the apartment in this case’s purchase price of KRW 9 million by F’s brokerage (hereinafter “sale contract of the apartment in this case”).

(2) On December 24, 2015, the Plaintiff received from F the documents necessary for the change of ownership, such as the instant apartment supply contract and the Defendant’s identification card copy, etc.

C. On December 24, 2015, the Plaintiff paid KRW 34,100,00 in sales contract amount and KRW 1,489,100 in the name of the Defendant and KRW 34,100 in the balcony expansion contract amount, respectively, to C. (2) On February 21, 2017, the Plaintiff paid KRW 2,978,200 in the part payment of balcony expansion work.

The Defendant, on June 5, 2018, requested on June 5, 2018, to change the name of the purchaser of the instant apartment, and the right to sell the instant apartment was transferred to G and H.

[Ground of Recognition] Facts without dispute, Gap 1 to 7 and 13 evidence (including branch numbers in case of additional number), the witness F's testimony and the purport of the whole pleadings

2. Determination on the cause of the claim

A. The gist of the cause of the claim is to seek payment of the following money to the Defendant on the premise that the sales contract of the instant sales right has expired.

1) [1] The Defendant claiming a return of unjust enrichment: ① KRW 9 million for the purchase price of the right to sell in lots paid by the Plaintiff to F; ② KRW 34,100,00 for the sales contract paid by the Plaintiff to F in the status of the buyer, ② KRW 1,489,100 for the balcony expansion construction contract, and KRW 2,978,200 for the balcony expansion construction.