The defendant's KRW 66,113,00 for the plaintiff and its 5% per annum from August 29, 2018 to May 28, 2020.

1. Comprehensively taking account of the purport of the entire argument in Gap evidence No. 1 as to the cause of the claim, the plaintiff entered into a contract with Nonparty D as a contractor on April 13, 2018, and the defendant as joint and several surety to supply ready-mixeds to "the construction site of Southern Navy Eth (hereinafter "the construction site of this case")". According to the above contract, the plaintiff entered into a contract with the same year from April 2, 2018.

8. Around 28.28 supplied ready-mixed equivalent to the sum of KRW 183,95,000, but only KRW 117,882,00 among them may be accepted as constituting 66,113,00 of the unpaid amount.

According to the above facts, the defendant is obligated to pay as a joint and several surety the above unpaid amount of KRW 66,113,00 and damages for delay calculated by the rate of 5% per annum under the Civil Act from August 29, 2018 to May 28, 2020, the delivery date of the payment order in this case, and 12% per annum under the Act on Special Cases concerning the Promotion, etc. of Legal Proceedings from the next day to the date of full payment.

2. It is so decided as per Disposition by the assent of all participating Justices on the ground that the plaintiff's claim of this case is reasonable.