2. The plaintiff's claim is dismissed.

3. All costs of the lawsuit shall be borne by the Plaintiff.

A. The Plaintiff’s assertion 1) C stipulates that the principal and interest borrowed from the Plaintiff from February 9, 2013 to August 26, 2016 shall be KRW 800 million as of January 23, 2017, and the maturity date shall be March 21, 2017; and the interest rate shall be set at 2% per month as of March 21, 2017 (Evidence 1-1; hereinafter “the instant loan certificate”).

A) The Defendant, the father of C, affixed a seal on the “Joint Guarantee” column of the above loan certificate, and jointly and severally guaranteed the above loan certificate, and C, around February 8, 2017, issued the above loan certificate to the Plaintiff. (2) Even if the Defendant did not have any joint and several liability as above, the Defendant ratified the obligation of joint and several liability for the Plaintiff later.

3. Therefore, the defendant, who is a joint and several surety, is liable to pay 80 million won and delay damages to the plaintiff.

B. The defendant's assertion that the defendant did not sign and seal the "joint guarantor" column of the loan certificate of this case, and C forged the above part, and there is no fact that the defendant ratified the joint and several guarantee obligation of the plaintiff.

2. Determination

A. Among the loan certificates of this case, the authenticity of the part in the defendant's name and the defendant's joint and several sureties 1) Gap evidence 1 and 6 (including paper numbers, hereinafter the same shall apply)

(1) According to the purport of the entire pleadings and arguments, ① the loan certificate of this case was written as of March 21, 2017, with the content that C borrowed from the Plaintiff to August 26, 2016 as KRW 800,000,000,000 for the principal and interest that C borrowed from the Plaintiff from February 9, 2013 to August 26, 2016; and the interest rate was written as of January 23, 2017, with the content that is set at 2% per month, and “debtor” was written as of January 23, 2017; the name and seal of C was written and sealed; “joint guarantor” was written and sealed by the Defendant’s name and seal seal stamp; ② the Plaintiff received the loan certificate of this case from the Defendant, the Defendant’s personal seal impression and Defendant’s resident registration certificate issued directly from the Defendant on February 6, 2017, and the Defendant’s resident registration certificate issued as of each resident registration certificate.