1. The Defendant’s KRW 1,200,791,150 to the Plaintiffs and 6% per annum from September 6, 2016 to November 3, 2017.

1. Basic facts

A. On June 29, 2010, the Plaintiffs concluded a project agreement with the Defendant on the supply of and demand for the construction of an internationalized complex M1 block compound (hereinafter “instant building”) located in Yeonsu-gu, Yeonsu-gu, Incheon (hereinafter “instant joint supply and demand agreement”) by organizing a joint supply and demand organization (hereinafter “instant joint supply and demand organization”) representing Plaintiff R1 Construction Co., Ltd. (hereinafter “Plaintiffs Construction”).

At the time of the conclusion of the above project agreement, the above joint supply and demand organization consisting of six members, including the non-party joint supply and demand company (including the non-party joint supply and demand company) corporation, the joint purchase and demand company (hereinafter referred to as the "joint purchase and demand company"), the non-party joint purchase and demand company (hereinafter referred to as the "the plaintiffs"), but the above three joint purchase and demand company (excluding the plaintiffs) has withdrawn later. Accordingly, the plaintiffs and

After several changes in the business plan, the Plaintiffs commenced the instant construction work on September 2012. On December 14, 2012, the Plaintiffs prepared a contract agreement set forth in KRW 42 months (from September 2012 to March 2016), contract price 491,343,09,044 (excluding value-added tax) from the date of commencement of the construction period with the Defendant on December 14, 2012.

(hereinafter referred to as the “instant construction contract” by referring to the foregoing project agreement and the contract agreement. The contents relating to this case in the said project agreement and the contract are as follows:

(hereinafter referred to as “A” refers to the Defendant, and “B” refers to the Plaintiffs respectively. Article 7 of the Business Agreement [Adjustment of Contract Amount] (1) of the Project Agreement does not increase the contract amount for construction works (construction cost, design cost, sale cost, etc.) even if there are reasons such as price fluctuation, design change, etc.

Article 3 [Construction Supervisor] (1) of the General Conditions of the Contract Agreement (hereinafter referred to as the "Construction Supervisor") may appoint a person who performs the following activities (hereinafter referred to as the "Construction Supervisor") to supervise him/her on his/her own or on his/her behalf in order to ensure the proper implementation

1. Supervising and attending the general construction work;

2. To perform the contract: