The judgment of the first instance, including the plaintiffs' claims changed in this court, is modified as follows.

1. Basic facts

A. On March 14, 2012, Plaintiff B entered into a sales contract to purchase KRW 589 million of the purchase price (hereinafter “instant sales contract”). Plaintiff B paid KRW 60 million to E on the date of the contract according to the instant sales contract. The remainder amount of KRW 529 million was paid by Plaintiff B, who sold a house in the name of the said land under the title of E, and paid the purchase price.

B. On April 25, 2012, Plaintiff B reported to the head of Bupyeong-gu Gun that seven houses with consent (hereinafter “instant houses”) will be constructed on the ground of the instant land under the name of Geumcheon-gu Gun. From March 2013, Plaintiff B performed the instant new house construction on the ground of the instant land, and suspended the instant construction after completing three building works and two building works.

C. On August 10, 2016, Plaintiff B entered into a construction contract with Defendant C (Appointed Party) (hereinafter “Defendant C”) (hereinafter “Defendant C”), setting the total construction cost of the remaining concrete works of the instant electric power resource housing among the instant new source housing construction works interrupted as above, as a total of KRW 150 million (hereinafter “instant construction contract”). The main contents of the instant construction contract are as follows.

The scope of construction: Defendant C, all of the remaining concrete construction works of the instant electric power plant, shall have to complete concrete construction works, such as the remaining construction works of the instant electric power plant T, Udong (attached Form 6, 7), V, W Dong (attached Form 1, 2 attached Form 1, 2), retaining walls based on underground space, etc., with a total of KRW 98 million.

Defendant C’s agreed construction cost of KRW 40 million, total construction cost of KRW 5 million (in advance payment), total construction cost of KRW 45 million (in advance payment) and prepaid payment of KRW 3 million.