1. All of the plaintiffs' claims are dismissed.

2. The costs of lawsuit are assessed against the plaintiffs.

1. The key points of the plaintiffs' assertion are the siblings of the deceased M (hereinafter "the deceased") or their successors.

The Defendant, even though he was not a relative of the deceased, was registered as the only child of the deceased on the family relations register after the deceased died, withdrawn KRW 323,00,000 from the account in the name of the deceased.

Therefore, the defendant is obligated to return the above money to the true inheritor according to his share of inheritance.

2. The Plaintiffs were not the deceased’s children, and accordingly, the Plaintiffs filed the instant claim on the premise that they were the deceased’s inheritors.

However, according to the statements in Eul evidence Nos. 7 through 9 (the results of genetic appraisal against the deceased and the defendant), the defendant is recognized as the deceased's child. Thus, the plaintiffs' assertion is without merit without examining the remaining points.

3. In conclusion, the plaintiffs' claims against the defendant are without merit, and it is so decided as per Disposition.