A. The plaintiff is a corporation that operates indoor construction business, etc. in Busan Dong-gu C, and the defendant is a corporation that operates construction business, etc. in Yangsan-si D.

B. On October 17, 2014, the Defendant and E Co., Ltd. (hereinafter “E”) entered into a contract with F Co., Ltd. (hereinafter “F”) on setting the construction cost as KRW 12,864,39,000 with respect to the construction of Gtel (hereinafter “Gtel or officetel construction”) and the construction cost as KRW 12,864,39,000. On September 8, 2015, the Defendant and E Co., Ltd entered into a modified contract with H, I, and J as joint contractor with respect to electrical construction, telecommunication, and fire fighting construction among officetels construction works.

C. On February 29, 2016, Defendant and E entered into a contract with the Plaintiff, among officetels construction works, to set the construction cost as KRW 841,647,400 with respect to the construction cost as KRW 841,647,400, and entered into a modified contract on May 15, 2016 with the effect that the construction cost shall be reduced to KRW 540,706,650, and the construction cost shall be reduced to KRW 99,00,00,000.

Defendant and E paid 540,706,650 won (=540,706,650 won) out of total of 639,706,650 won for light-scale mold construction works (=540,706,650 won) to the Plaintiff, and the remainder paid 540,706,650 won to the Plaintiff in lieu of 1st office of Gtel.

E. Around April 2017, Defendant and E agreed with F and E to determine payment in substitutes as KRW 133,857,000, and the Plaintiff entered into a payment in substitutes contract with F and G officetels L Co., Ltd. (hereinafter referred to as “L”) and with the Plaintiff’s acceptance of the Plaintiff as the actual owner of the instant officetel and the instant officetel K, upon completing the registration of ownership transfer in the future.

F. Meanwhile, the Plaintiff and the Defendant, and the Plaintiff, on August 24, 2016, estimated the amount of 14,364.