A. On September 26, 2016, the Defendant concluded a contract with D Co., Ltd. (hereinafter “D”) for installation of heating and cooling equipment and electric heat exchange equipment during the instant construction work (hereinafter “instant construction”). From February 26, 2016 to November 2017, the Defendant concluded a contract by setting the construction cost of KRW 330,000,00 (including additional tax) with respect to installation of heating and electric heat exchange equipment during the instant construction work, from the date of the contract period to February 26, 2016.

B. On April 4, 2017, Non-Party F Co., Ltd. (hereinafter “Non-Party F”) agreed to enter into a contract for the instant construction project with the Defendant around April 4, 2017. On April 4, 2017, the Plaintiff entered into a contract with the Plaintiff by setting the construction cost of KRW 330,00,00 (including additional tax) during the instant construction project as the contract period from April 4, 2017 to December 31, 2017 (hereinafter “instant contract”). Accordingly, the terms of the contract between the Plaintiff and the Defendant were changed from “Defendant” to “non-party Company” and the contract period from “from February 26, 2016 to November 11, 2017 to “from April 1, 2017”;

C. On August 1, 2017, Nonparty Company concluded a contract with the Defendant for the instant construction work with the period fixed from April 4, 2017 to November 30, 2017, by setting the construction cost of KRW 1,391,50,000 (the already paid KRW 501,00,000,000, which is included in the contract amount) as indicated in a provisional contract between the Defendant and the Plaintiff, to the effect that the construction cost paid by the Defendant to a trader that directly entered into the contract is included in the contract amount of August 1, 2017 between the Nonparty Company and the Defendant.)

On October 21, 2017, the Plaintiff agreed to install additional air conditioners (hereinafter “additional Works”) between the Nonparty Company and the construction cost of KRW 7,700,00 (including additional duties).