1. The plaintiff's appeal is dismissed.

2. Upon the plaintiff's preliminary claims added by this Court:

(a) C and the defendant;

1. The reasoning for this part of the reasoning is the same as that of the judgment of the court of first instance, and thus, this part of the reasoning is cited pursuant to the main sentence of Article 420 of the Civil Procedure Act.

2. Judgment on the main claim

A. The Plaintiff’s assertion holds a loan claim amounting to KRW 210 million against C.

However, C concluded a title trust agreement with the Defendant, who is an son, and provided the Defendant with a purchase fund of KRW 250 million, thereby allowing the Defendant to purchase the instant apartment as a party to the instant sales contract and complete the registration of ownership transfer thereof.

Since the transfer of ownership by the title trust agreement between C and the defendant constitutes a contract title trust in which the seller is bona fide, the defendant is obligated to acquire the ownership of the apartment of this case and return the amount equivalent to the purchase fund to C in unjust enrichment.

Nevertheless, since C does not exercise the above claim against the defendant for return of unjust enrichment, the plaintiff, the creditor of C, by subrogation, sought payment of the above unjust enrichment amounting to KRW 255 million against the defendant and delay damages.

B. Determination 1) In a case where the obligee’s insolvent creditor’s right to the obligor, which is to be preserved by subrogation, is a monetary claim against the obligor in subrogation of the obligor, the obligee may exercise the obligor’s right to the third obligor on behalf of the obligor only when the obligor is insolvent (see, e.g., Supreme Court Decision 2008Da76556, Feb. 26, 2009). In addition, the determination as to whether the obligor is liable to pay the obligor’s obligation at the exercise of the obligee’s subrogation right ought to be based on the time of the closing of argument (see, e.g., Supreme Court Decisions 75Da1086, Jul. 13, 1976; 2010Da93202, Feb. 23, 2012). Based on the foregoing legal doctrine, the foregoing legal doctrine is based on the entry of evidence No. 16, and the first instance court’s P Bank, Q Bank, Bank, S Bank, and I Bank’s reply order.