1. All of the plaintiffs' claims are dismissed.

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

1. Basic facts

A. On August 10, 2010, the NetworkF completed the registration of transfer of ownership on the ground of the gift on August 10, 2010 (hereinafter “instant gift”) from August 10, 2010 with respect to the 1/2 shares of each real estate listed in paragraph 1 of the attached Table to Defendant C and D (Defendant C’s wife).

B. On February 8, 2011, the Deceased drafted a testamentary document stating that each of the real estate listed in [Attachment C] Nos. 2 and 3 should be bequeathed to Defendant E (Defendant C’s children).

(hereinafter “instant legacy”). Accordingly, on January 13, 2014, Defendant E completed the registration of ownership transfer based on legacy on December 30, 2013.

(hereinafter referred to as "the transfer registration of ownership" in this case, including the transfer registration of ownership in paragraph (1).

On December 30, 2013, the Deceased died, and his heir had wife G and children, Defendant C, H and I as his heir.

[Ground of recognition] Facts without dispute, Gap evidence 1 through 5, Eul evidence 6 (including branch numbers; hereinafter the same shall apply), the purport of whole pleadings

2. The plaintiff's assertion and judgment

A. The gist of the Plaintiff’s assertion is that the deceased had no mental capacity at the time of the instant donation and testamentary gift, and thus the said donation and testamentary gift are both null and void.

Therefore, the Defendants are obligated to cancel each of the above registrations of ownership transfer, which is null and void as to their respective shares of inheritance among each of the instant real estate to the Plaintiffs, the inheritor of the deceased.

B. Determination 1) “Legal capacity” refers to a mental ability or intelligence that can reasonably determine the meaning or outcome of one’s act based on normal perception and towing ability, and the existence or absence of a mental capacity ought to be individually determined in relation to a specific juristic act (see Supreme Court Decision 2001Da10113, Oct. 11, 2002). Meanwhile, the party asserting invalidation of a juristic act based on his/her legal capacity bears the burden of proof (see Supreme Court Decision 2009Da53093, 53109, Mar. 13, 2014).