1. All appeals filed by the plaintiff and the plaintiff succeeding intervenor are dismissed.

2. The costs of appeal are assessed against the Plaintiff and the Intervenor succeeding to the Plaintiff.

1. The plaintiff and the successor intervenor claimed the return of KRW 1,365,00,00 against the defendant at the first instance court. The court of the first instance rendered a judgment dismissing the part of KRW 455,934,254, which K received a collection order, and dismissed the remainder of KRW 909,065,746, and the plaintiff and the successor intervenor appealed only for KRW 909,065,746, which excludes the above dismissed part. Accordingly, only the part of KRW 909,065,746, excluding the above dismissed part, is subject to the judgment of this court.

2. The reasoning for the court’s explanation on this part of the underlying facts is as stated in Paragraph 1 of Article 420 of the Civil Procedure Act, except where “this court” in Section 7, 12, among the grounds for the judgment of the court of first instance, is deemed to be “court of the court of first instance.” Thus, this part of the reasoning for the judgment of the court of first instance is cited in accordance with

3. The parties' assertion

A. The Plaintiff and the Intervenor’s assertion that the Plaintiff paid KRW 1.4 billion to the Defendant during the period from March 10, 2011 to May 6, 2011 (hereinafter “instant performance guarantee”) is a performance guarantee, not related to the instant contract, paid by the Plaintiff and the Defendant pursuant to a joint agreement between the Plaintiff and the Defendant to newly construct officetels on the C site that was concluded on August 1, 2011 (hereinafter “instant joint agreement”). The said joint agreement was unnecessary, and the Plaintiff waived the claim for the return of the said performance guarantee. Therefore, the Defendant ought to return the amount of KRW 1,365,00,000 to the Plaintiff and the Intervenor.

B. The Defendant’s assertion that the instant performance guarantee was paid to C in connection with the sale of the property, and the Plaintiff did not prepare purchase funds under the instant contract, as well as prevented the Plaintiff from committing an illegal act of investing ten billion won out of C’s building and site as security with a loan of 20 billion won to the company unrelated to the Defendant. Accordingly, the instant contract was nonexistent.