1. The judgment below is reversed.

2. The plaintiff's appeal is dismissed.

3. Preliminary claims added by the lower court are as follows.

1. Judgment on the grounds of appeal

A. As to the assertion of misapprehension of the legal principle as to the interpretation of expression of intent, the lower court, based on its stated reasoning, determined that there was an agreement between the Plaintiff and the Defendant to extinguish at least all of the Plaintiff’s obligations pursuant to the final and conclusive judgment of the previous lawsuit, based on the empirical rule.

In light of the records, the above determination by the court below is just, and there is no error in the misapprehension of legal principles as to the interpretation of expression of intent.

B. Since the obligation to return unjust enrichment on the assertion of misapprehension of the legal principles as to the initial date of the payment for delay is an obligation for which the payment period is not fixed, the obligor is liable for delay only

(See) (See Article 387(2) of the Civil Act). The lower court determined that the Defendant was liable to pay to the Plaintiff 45,000,000 won and damages for delay, which the Plaintiff transferred to the Defendant as unjust enrichment, as unjust enrichment, on November 29, 2013, since it cannot be deemed that the sales contract was concluded between the Plaintiff and the Defendant. Furthermore, the lower court determined that the Plaintiff was liable to pay damages for delay from November 29, 201

However, according to the records, the above KRW 45,00,000 can be known to the defendant that the copy of the plaintiff's grounds of appeal stating the purport of claiming the return on the ground that the above KRW 45,000 constitutes unjust enrichment, was served on June 29, 2015, and there is no reason to acknowledge that the plaintiff filed a claim for return on the ground

Therefore, in light of the aforementioned legal principles, the Defendant is liable for delay on June 29, 2015, when requested for payment of KRW 45,000,000, and the initial date of calculating damages for delay should be June 30, 2015.

Nevertheless, the lower court ordered the payment of damages for delay from November 29, 2013, which the Plaintiff sought, at the time when the obligation to return unjust enrichment arose.