A. The Plaintiff sought the return of the lease deposit to the primary Defendant who entered into a lease agreement with the Plaintiff, and sought the return of the lease deposit to the primary Defendant on the premise that the repayment obligation of the lease deposit is not recognized.

The court of first instance accepted the plaintiff's claim against the primary defendant and dismissed the claim against the primary defendant, and the primary defendant appealed against this.

B. A subjective preliminary co-litigation is a form of litigation in which all co-litigants settle a dispute between each other in relation to the same legal relationship in a lump sum without contradiction (Article 70(2) of the Civil Procedure Act). In a subjective preliminary co-litigation, where one of the primary co-litigants and the preliminary co-litigants files an appeal in a subjective preliminary co-litigation, the confirmation of the claim part concerning other co-litigants is interrupted, and the claim part concerning other co-litigants is transferred to the appellate court and are subject to adjudication (see Supreme Court Decision 2009Da4355, Feb. 24, 2011). If an appeal is filed against any one of the primary co-litigants and the preliminary co-litigants, the part of the claim against other co-litigants is transferred to the appellate court and subject to adjudication (see Supreme Court Decision 2006Du17765, Mar. 27, 2008).

In light of the above legal principles, if a claim against the primary defendant is not accepted, the plaintiff filed a lawsuit to the effect that the claim against the primary defendant is accepted, and the lawsuit of this case is a subjective preliminary co-litigation relationship. Even if only the primary defendant filed an appeal against the plaintiff, the part of the claim against the primary defendant is transferred to the appellate court, and is subject to adjudication.

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