1. The Plaintiff (Counterclaim Defendant) paid KRW 139,483,244 to the Defendant (Counterclaim Plaintiff) and its related amount from October 11, 2018 to November 21, 2019.

A principal lawsuit and a counterclaim shall be deemed simultaneously.

1. Facts of recognition;

A. A. Around July 2014, the Defendant entered into a construction contract with the Plaintiff, Jeju-si, with respect to the construction of a new site neighborhood living facility and a detached house (hereinafter “instant building”) (hereinafter “instant construction”) (hereinafter “instant construction contract”), under which the contract amount is KRW 716,00,000 (excluding value-added tax), and the construction period is from July 7, 2014 to October 31, 2014, and the delay damages rate is 1/1,000 to the Plaintiff (hereinafter “instant contract”).

The instant contract includes the following:

Article 14 (Adjustment of Contract Amount Due to Modification of Design) (1) When the contents of a design do not coincide with the condition of the construction site, or are unclear, omitted or erroneous, or unexpected circumstances in relation to construction occur or the project plan is modified, the design shall be modified.

(2) Where an increase or decrease in construction volume occurs due to the modification of a design under paragraph (1), the contract amount shall be adjusted according to the following standards:

1. The unit price for a new item not included in the detailed statement of construction price shall be the unit price computed as at the time of design modification; and

2. The rate specified in the calculation sheet shall apply to the general management expenses and interest rates for increased or decreased construction works;

B. The instant building was approved for use on June 4, 2015.

C. The Defendant paid the Plaintiff KRW 787,60,000,000, which added value added tax to the said contract price as the construction price of the instant case.

[Reasons for Recognition] Unsatisfy, Gap evidence 2, 5, 9 (if a number is included, including branch numbers; hereinafter the same shall apply), the purport of the whole pleadings

2. Summary of the parties' arguments

A. The design was modified after the commencement of the instant construction project. Accordingly, the Plaintiff completed the instant construction project by additionally bringing KRW 257,200,000 into KRW 257,200,000, and the Defendant should pay KRW 257,200,000 in addition to the contract amount already paid to the Plaintiff.

B. Defendant 1’s main office.