The defendant's appeal is dismissed.

Expenses for appeal shall be borne by the defendant.

The purport of the claim and the purport of the appeal.

1. The reasons for the acceptance of the judgment of the court of first instance are as follows, except for the addition of the following “2. additional determination” to the assertion that the defendant added or emphasized by the court of first instance, and thus, they are cited by the main sentence of Article 420 of the Civil Procedure Act.

2. Additional determination

A. The gist of the Defendant’s assertion and the Defendant concluded a lease transfer contract on the instant real estate (hereinafter “instant transfer contract”) around August 2016. Since the Plaintiff, the Defendant, and the lessor agreed to increase the lease deposit in KRW 10 million on or around July 8, 2017 and to prepare a new lease contract between the Plaintiff and the lessor, the Defendant fulfilled his/her duty as the lease transferor.

Since then, the Plaintiff, a transferee, was unable to pay KRW 5 million out of the increased lease deposit, and it is not the Defendant’s responsibility that the lease contract was not prepared between the Plaintiff and the lessor.

B. The following facts or circumstances are established based on the evidence Nos. 1, 3, 4, and 3 and 5 of the court below's ruling. <1> The plaintiff paid KRW 50 million to the defendant according to the transfer contract of this case, i.e., the plaintiff paid KRW 50 million to the defendant upon a lessor's request for the increase of the lease deposit of this case; <2> The payment of the lease deposit of this case was made under the premise that the plaintiff can receive the lease deposit from the lessor;3) the plaintiff, the defendant, and the lessor did not actually enter into the lease contract between the plaintiff and the lessor;4) the plaintiff could not demand the return of the lease deposit of this case to the defendant, and the lessor received the payment from the defendant.