Of the ancillary claims of the lower judgment, the part on the second claim on the ground of violation of the obligation for completion of responsibility and the third claim.

The grounds of appeal (to the extent of supplement in case of supplemental appellate briefs not timely filed) are examined (to the extent of supplement in case of supplemental appellate briefs not timely filed) by the Plaintiff and Defendant.

1. As to the third claim among the conjunctive claim

A. As to the grounds of appeal Nos. 1 and 2, the lower court determined as follows on the grounds as stated in its reasoning.

(A) In full view of the circumstances, etc. under which Article 8 of the instant development project agreement clearly provides that “the construction period shall be 15 months after the commencement of the construction project,” the Defendant is obligated to complete the construction of the instant building within 15 months after the commencement of the construction project, unless an inevitable cause, such as a natural disaster, exists pursuant to the instant development project agreement.

Where the Defendant, who is in charge of the construction of the entire building of this case under the instant development project agreement, fulfills his/her duty to complete his/her responsibility, it is evident that the building is completed and the registration of ownership preservation has been completed, and that the Plaintiff would recover part payments or obtain at least the first priority collective security right.

However, as long as the Defendant ceased construction on the ground that he/she had fulfilled his/her responsibility and failed to receive construction payment from A Co., Ltd. (hereinafter “A”), so long as the Plaintiff could not obtain and exercise a security for the instant building, there is a proximate causal relationship between the Defendant’s failure to perform his/her responsibility and the Plaintiff’s failure to obtain a security.

(B) Although the Defendant asserts that there is no proximate causal relation between the Defendant’s failure to perform the duty to complete construction and the Plaintiff’s failure to obtain security rights, since the registration of ownership preservation cannot be completed as long as the direct construction part of the instant building was not completed even if he/she performs all the construction that he/she received.