1. The plaintiff's appeal is all dismissed.

2. The costs of appeal shall be borne by the Plaintiff.

The purport of the claim and appeal is the purport of the appeal.

1. Basic facts

A. Defendant B is a person who resides in the first unit of the apartment house D (hereinafter referred to as “instant building”) located in Yangyang-si, and Defendant C is the owner of the instant building F (hereinafter referred to as “instant real estate”).

B. On August 2017, water leakage from boiler pipes of the instant building E led to the occurrence of damage to the water, such as the ceiling of the instant building F, remote areas, and door boards, etc.

C. Upon receiving a request from Defendant B to replace the ceiling, remote area, and market board of the instant building F (hereinafter “instant construction”), the Plaintiff agreed to perform the instant construction work at KRW 5.6 million for the construction cost.

Defendant B received insurance money of KRW 5.6 million from G Co., Ltd., and delivered it to Defendant C, and Defendant C paid KRW 2.5 million to the Plaintiff on September 4, 2017.

[Ground of recognition] Unsatisfy, entry in Gap evidence 1 through 4 (including each number for a case with a serial number), the purport of the whole pleadings

2. The parties' assertion and judgment

A. The Plaintiff’s assertion 1) The Plaintiff concluded the instant construction contract with Defendant B, and completed the instant construction, but failed to receive KRW 3.1 million among the construction cost. As such, Defendant B is obligated to pay the Plaintiff the construction cost unpaid to the Plaintiff as a contracting party. Defendant C has a duty to jointly pay KRW 3.1 million to the Plaintiff by paying only a part of the construction cost despite having received the payment of insurance money from the Defendant B without any legal cause. As such, Defendant C is obligated to jointly pay the remainder of KRW 3.1 million to the Plaintiff as a return of unjust enrichment. 2) The Plaintiff’s assertion by the Defendants did not complete the instant construction and the part of the construction completed requires reconstruction. As such, the remainder of the construction cost may be paid before the Plaintiff completed the instant construction.