The judgment below

Among them, the part against the Defendant (Counterclaim) regarding the main lawsuit is reversed, and this part of the case is remanded.

The grounds of appeal are examined.

1. As to the part against the Defendant (Counterclaim Plaintiff; hereinafter “Defendant”) regarding the main lawsuit of the Plaintiff (Counterclaim Defendant; hereinafter “Plaintiff”)

A. Where each party should return a bilateral contract becomes null and void and each party acquires the bilateral contract, and if the obligation to return is enforced first, it would result in a violation of the principle of equity and good faith. Therefore, it is reasonable to deem that each party’s obligation to return is in a simultaneous performance relationship.

(2) In light of the above legal principles, the court below erred by misapprehending the legal principles as to the establishment of a concurrent performance defense right, and thereby exceeding the bounds of the principle of free evaluation of evidence, and by exceeding the bounds of the principle of free evaluation of evidence, as otherwise alleged in the ground of appeal. In so doing, the court below did not err by misapprehending the legal principles as to the establishment of a concurrent performance defense right, as otherwise alleged in the ground of appeal. In so doing, it did not err by misapprehending the legal principles as to the establishment of a concurrent performance defense right, as otherwise alleged in the ground of appeal.

(1) In a case where a single contract or an agreement added thereto (see, e.g., Supreme Court Decisions 2010Da47438, Oct. 14, 2010; 2015Da32585, Oct. 29, 2015). Meanwhile, in a case where multiple rights and obligations are closely connected with one another for the same economic purpose, the part corresponding to the typical contract, etc. under the Civil Act is separated from one another, and the obligation under the Civil Act is not deemed as a simultaneous performance relationship, and the other party’s several obligations and obligations are comprehensively included in a single contract or agreement added thereto.