All appeals are dismissed.

The costs of appeal shall be borne by the Defendants and the co-defendant A of the first instance trial, J and K.

The grounds of appeal are examined.

1. Examining the reasoning of the lower judgment in light of the relevant legal principles and records as to the grounds of appeal on the good faith principle, the lower court is just and acceptable to determine that the Plaintiff’s claim for removal of the instant building cannot be deemed as contrary to the good faith principle. In so doing, it did not err by misapprehending the legal principles on

2. As to the grounds of appeal relating to the requirements for establishing legal superficies or customary legal superficies

A. Legal superficies under Article 366 of the Civil Act is established when land and its ground buildings belong to the same owner at the time when a mortgage is established, and where a mortgage is established before there is a seizure for compulsory auction or a provisional seizure prior to such seizure for the land or its ground buildings which become the object of a compulsory auction, and where the mortgage is extinguished due to a compulsory auction thereafter, when the land and its ground buildings belong to the same owner as at the time of the establishment of such mortgage, legal superficies is established under customary law

(See Supreme Court Decision 2009Da62059 Decided April 11, 2013, etc.). Meanwhile, in a case where a building on the ground was constructed by a landowner at the time when a mortgage is established with respect to the land, and where the building was developed to the extent that the size and type of the building could be anticipated to be external form, even if it did not reach the degree that it could be seen as an independent building in light of social concept, the mortgagee may expect the building to be completed, so that the mortgagee may expect the building to be completed, and thus, it is reasonable to determine the establishment of statutory superficies or customary statutory superficies, because it is recognized that it does not incur unexpected damage even if it is necessary to maintain the building

On the other hand, even if the landowner started the construction of a building on the ground at the time when the mortgage was established on the land, the construction has not been developed to the extent above.