The appeal is dismissed.

The costs of appeal are assessed against the Plaintiff.

The grounds of appeal are examined.

1. Regarding ground of appeal No. 1

A. The lower court rejected the Plaintiff’s assertion that the act of joint and several surety A’s debt owed to the Defendant constitutes “the act of having known that the debtor would prejudice any rehabilitation creditor or any rehabilitation secured creditor” under Article 100(1)1 of the Debtor Rehabilitation and Bankruptcy Act (hereinafter “Rehabilitation Act”), on the following grounds.

On December 29, 2014, the period for reporting rehabilitation claims, the Defendant reported the joint and several several surety claims against A as rehabilitation claims, and the Plaintiff, the administrator of A, raised an objection to all of the above claims.

Inasmuch as the above claim constitutes “claim with executive title” under Article 174(1) of the Debtor Rehabilitation Act, the Plaintiff, who is the opponent, may raise an objection only by means of “litigation that can be carried out by the debtor” within one month from January 22, 2015, the end of the investigation date.

(1) Article 174(1) and (3) of the Debtor Rehabilitation Act and Article 170(2) of the same Act. However, inasmuch as the Plaintiff did not raise an objection under the aforementioned legal proceedings within the said period, it shall be deemed that the said claim for objection was recognized.

(Article 174(4) of the Debtor Rehabilitation Act. Accordingly, insofar as a dispute over the aforementioned disputed claims takes effect, the Plaintiff, who is the custodian, cannot contest the existence of the joint and several surety claim by exercising the avoidance power any longer.

B. Examining the relevant legal principles and records, the lower court did not err by misapprehending the legal doctrine on interpretation of Article 174 of the Debtor Rehabilitation Act, contrary to what is alleged in the grounds of appeal.

2. Regarding ground of appeal No. 2

A. According to Article 100(1) of the Debtor Rehabilitation Act, an act subject to avoidance is, in principle, an act of the debtor.

However, even if there was no debtor's act, the creditor or the third party has been in collusion with the debtor.