Therefore, barring special circumstances, the Defendant is obligated to pay the Plaintiff the borrowed amount of KRW 1.75 billion and the delay damages for the borrowed amount of KRW 1.75 billion.

2. Judgment on the defendant's defense

A. The defendant's defense of repayment is proved to have paid KRW 90 million out of the above borrowed money. Thus, according to the Eul evidence No. 1 (including the provisional number), the defendant paid KRW 90 million to the non-party C over 20 times between October 7, 2015 and May 15, 2018, although it is recognized that the defendant paid KRW 90 million to the non-party C during 20 times, there is no evidence to acknowledge that the defendant paid the above borrowed money in the name of the repayment of the above borrowed money. Thus, the defendant's defense of payment is without merit.

Rather, comprehensively taking account of the aforementioned evidence and the purport of the entire pleadings, the Plaintiff borrowed KRW 300 million from C on September 7, 2015 to the Defendant, and the Defendant agreed to pay KRW 4,500,000 on behalf of the Plaintiff in lieu of the Plaintiff each month as interest on the said borrowed money, and thus, the above KRW 90,000 is deemed to have been paid as interest repayment for C.

B. The defendant's defense of set-off is a defense that the defendant set-off against the above plaintiff's loan claim in excess of KRW 431.7 million against the plaintiff and the non-party D, who are the plaintiff's children, with the overdue loan claim in excess of KRW 431.7 million. Thus, the defendant's defense of set-off is without merit without further examination of the remaining issues.

3. Accordingly, the defendant's loan amounting to the plaintiff 1.765 billion won in total and the loan date respectively.