1. The plaintiff's appeal is dismissed.

2. The plaintiff's supplementary claim is dismissed in this court.

3...

1. The reasoning for this part of the lower court’s reasoning is the same as that of “1. Basic Facts” in the corresponding part of the first instance judgment from 4 to 18. Thus, this part of the reasoning is acceptable in accordance with the main sentence of Article 420 of the Civil Procedure Act.

2. Main claim;

A. 1) The Defendant’s assertion on this safety defense is based on the Defendant’s primary claim, which is about 55 square meters of the fourth floor of the instant building among the instant buildings (hereinafter “5 square meters of the instant building”).

A) The Plaintiff seeks confirmation of ownership, and this is intended to make registration of ownership preservation in the name of the Plaintiff. However, even if the Plaintiff received confirmation of ownership of 55 square meters of the fourth floor among the instant buildings, it is not possible under the Registration of Real Estate Act to separate only the above 55 square meters of the instant buildings since it was a detached house (multi-family house) without a separate registration, and to seek confirmation of ownership of a building that has not been created in the building register, it does not constitute a "registration under the Registration of Real Estate Act" that can apply for registration of ownership preservation. Therefore, the Plaintiff’s primary claim seeking confirmation of ownership of 55 square meters of the fourth floor among the instant buildings is unlawful because there is no benefit of confirmation. In addition, even according to the Plaintiff’s assertion, even if the Plaintiff participated in the primary claim of this case, it is not finalized as the Plaintiff’s co-ownership right, and it is not a threat to the Plaintiff’s right or a legal interest in the instant building.