1. The defendant (Counterclaim C)'s appeal is dismissed.

2. The costs of appeal shall include all the parts related to Defendant B.

1. Scope of adjudication of this court;

A. The Plaintiff sought the return of the lease deposit to Defendant B, who entered into a lease contract with himself/herself, and sought the return of the lease deposit to Defendant C under the condition that the claim for return of the lease deposit against Defendant B is not recognized.

This form of lawsuit is a subjective preliminary co-litigation under Article 70(1) of the Civil Procedure Act, where a claim against a part of the co-litigants is legally incompatible with a claim against another co-litigants.

B. The court of first instance dismissed the Plaintiff’s claim against the primary Defendant B, and filed an appeal against the conjunctive Defendant C as to the acceptance of the claim against the primary Defendant C.

A subjective preliminary co-litigation is a form of litigation in which all co-litigants resolve disputes between each other in the same legal relationship without contradiction, and they shall render a judgment on the claims against all co-litigants (Article 70(2) of the Civil Procedure Act). In a subjective preliminary co-litigation, where either the primary co-litigants or any of the preliminary co-litigants files an appeal in a subjective preliminary co-litigation, the final and conclusive part of claims against other co-litigants shall also be prevented, and they shall be subject to adjudication by the appellate court (see Supreme Court Decision 2009Da4355, Feb. 24, 2011). If an appeal is filed against either the primary co-litigants or any of the preliminary co-litigants, the part of claims against other co-litigants shall also be subject to adjudication by the appellate court (see Supreme Court Decision 2006Du17765, Mar. 27, 2008).

In light of the above legal principles, the Plaintiff brought the instant lawsuit to the effect that if the claim against the Defendant B is not accepted, it would accept the claim against the Defendant C, which is legally incompatible with the claim, and eventually, the instant lawsuit is a subjective preliminary co-litigation.