A. The Plaintiff is a public corporation established under the Korea Coal Corporation Act for the promotion of the development of coal mines, the production, processing and sale of coal, and the operation of incidental business.

B. On December 22, 2010, the Plaintiff, the Defendant, and the Plaintiff Co., Ltd. (formerly changed: C; hereinafter “B”) entered into a contract with shareholders to establish D Co., Ltd. (hereinafter “D”) in order to promote overseas resources development, such as the development of mines in Mongolia. According to the said contract, the Plaintiff acquired 480,000 shares equivalent to 60% of D’s issued shares, and 160,000 shares amounting to 20% of the above shares, respectively.

C. D around July 30, 2014, as of July 28, 2015, the due date set from the National Bank of Korea (hereinafter “National Bank”) as of July 28, 2015, and around August 20, 2014, the due date set from the Korea Exchange Bank of Korea (hereinafter “Korea Exchange Bank”) as of August 20, 2015 and borrowed KRW 7.4 billion from the Korea Exchange Bank of Korea (hereinafter “Korea Exchange Bank”) as of August 20, 2015. On the same day, the Plaintiff provided a collateral guarantee service on each of the above loans amounting to KRW 2,090,000,000, and KRW 8,880,000,000 as the guarantee date.

On the other hand, around June 16, 2014, the defendant prepared an agreement with the purport that "where the plaintiff subrogated for the plaintiff due to impossibility of repayment of D with respect to KRW 1.9 billion borrowed by D, an amount equivalent to 20% of the amount equivalent to D shares owned by the defendant out of the principal and interest the plaintiff subrogated for the plaintiff (hereinafter "instant agreement"), and around August 20, 2014, "where the plaintiff subrogated for the plaintiff due to impossibility of repayment of D with respect to KRW 7.4 billion borrowed by D, an amount equivalent to 20% of the amount equivalent to D shares owned by the defendant out of the principal and interest the plaintiff subrogated for the plaintiff (hereinafter "instant agreement 2", and collectively, "each of the instant agreements").