A. On April 28, 2014, the Plaintiff entered into a contract for the purchase and sale of one ethyl Co., Ltd. and the term of the contract from April 28, 2014 to June 30, 2014 (hereinafter “instant contract”). The Plaintiff entered into a contract for the purchase and sale of the Chuncheon C Apartment Co., Ltd. (hereinafter “instant contract”) with the contractual amount of KRW 500,000,000 (hereinafter “instant contract”).

(A) After the conclusion of the instant contract, one ethyl was changed to the real name of a stock company, but on June 13, 2016, it was changed to the trade name again on June 13, 2016. hereinafter “One ethyl” regardless of whether it was before or after the mutual change.

At the time of the instant contract, Defendant B Co., Ltd. (hereinafter “Defendant B”) distributed profits under the terms and conditions of the instant contract to the Plaintiff and Defendant B to the Plaintiff and Defendant B 50:50; ② Defendant B proceeds from the removal of the instant contract within the scope of KRW 60,000; and ③ When the Plaintiff cannot recover KRW 500,000,000 of the instant contract amount, Defendant B entered into an agreement with the Plaintiff as a joint and several surety to compensate the Plaintiff for the full amount of the instant contract amount (hereinafter “instant agreement”).

C. On April 28, 2014, the Plaintiff paid KRW 500,000,000 of the instant contract amount to Hanethyl Co., Ltd., but did not perform the removal construction under the instant contract, and the Plaintiff demanded to return the instant contract amount to Hanethyl Co., Ltd., the Plaintiff: (a) on April 2, 2015, Hanethyl Co., Ltd.: (b) prepared a memorandum of default stating that “I will pay the instant contract amount and interest for delay to the Plaintiff by July 15, 2015,” and deliver it to the Plaintiff.

On April 2, 2015, Defendant A also drawn up a lux note with the same content as the lux note that was drawn up and delivered to the Plaintiff (hereinafter “instant lux note”) and issued to the Plaintiff.