A. The Korea National Housing Corporation (the Korea National Housing Corporation and the Korea Land Corporation were merged with the Defendant on October 1, 2009; hereinafter referred to as the “Defendant”) obtained approval for a housing construction project plan that newly constructs public rental housing units on Gyeonggi Pable AB block around December 30, 2000.

B. Around May 2004, the Defendant completed the G Apartment-si B apartment (hereinafter “instant apartment”) and the period of mandatory lease of the instant apartment has expired with the lapse of the period of sale for sale. As the construction cost of the household corresponding to the 51.72m2m2 of the instant apartment, the Defendant calculated the construction cost of the household corresponding to the 51.72m2m2 of the instant apartment as KRW 66,260,00, and the construction cost of the household corresponding to the 59.92m2m2 as KRW 77,000, and accordingly, the Defendant calculated the construction cost of the household corresponding to the 59.92m2m2 of the instant apartment. Accordingly, the remainder of the Plaintiffs except the Plaintiff C as to each of the instant apartment indicated in the “Dong-si, number” column in the attached Table 2 among the instant apartment, D concluded each sales contract (hereinafter “each of the instant sales contract”).

C. The remaining Plaintiffs and D except the Plaintiff C paid each purchase price to the Defendant according to each of the instant sales contracts.

D On August 25, 2011, Plaintiff C transferred to Plaintiff C a claim for return of unjust enrichment with respect to the sale price set forth in 702 Dong 1501 among the instant apartment units, and notified the Defendant of the transfer of the above claim at that time.

[Ground of recognition] Facts without dispute, Gap evidence 1, 2, Eul evidence 3, 10, 11, the purport of the whole pleadings

2. The pre-sale conversion price of the instant apartment should be calculated in accordance with the standards prescribed by relevant statutes, such as the former Rental Housing Act (amended by Act No. 9863, Dec. 29, 2009). The Defendant set the excess amount as the parcelling-out price, and received each payment from the remaining Plaintiffs and D except the Plaintiff C, thereby unjust enrichment.