The part concerning the second preliminary claim is reversed, and this part of the case is remanded to the Seoul High Court.

1. As to the appeal as to the main claim, the plaintiff appealed to the main claim among the judgment below, but there is no entry of the grounds for appeal in the petition of appeal and no statement of the grounds for appeal is found even in the appellate brief.

2. As to the grounds of appeal on the first preliminary claim, the lower court rejected the Plaintiff’s claim for return of unjust enrichment, on the grounds the following grounds: (a) it is insufficient to readily conclude that the instant sales contract falls under the invalidity of validity as a matter of course; and (b) even if the obligee of the construction cost to be paid by the Plaintiff is the Defendant or D Co., Ltd. (hereinafter “D”), the registration of ownership transfer cannot be deemed as unjust enrichment.

The judgment below

In light of the records, the above determination by the court below is just, and contrary to the allegations in the grounds of appeal, the court below did not err by failing to exhaust all necessary deliberations or by misapprehending relevant legal principles, or omitting judgment.

3. As to the ground of appeal on the second preliminary claim

A. According to the reasoning of the judgment below, on September 23, 2009, the Plaintiff entered into a construction contract with D to construct a motor vehicle maintenance plant and a gas station on the instant land owned by D (hereinafter “instant construction”) and entered into an international trust trust agreement with an international trust company (hereinafter “international trust”) to secure the obligation for the construction payment on the same day, and completed an international trust registration on September 24, 2009 with regard to the instant land. ② The Plaintiff entered into an additional construction contract with D to increase the construction payment amount of KRW 1,372,250,000 between D and D on October 15, 2010; ③ the Plaintiff completed the construction of the instant building on October 21, 2010; and ③ the building of this case between D and international trust.