The appeal is dismissed.

The costs of appeal are assessed against the defendant.

The grounds of appeal are examined.

1. As to the assertion of misapprehension of the legal principles as to the objective scope of res judicata, the court below rejected the defendant's assertion that the lawsuit in this case is contrary to res judicata in relation to the judgment in the previous suit, on the ground that it does not conflict with the existence of the claim for return of unjust enrichment and the validity of extinctive prescription as to the joint and several obligors is merely a premise, and it cannot be seen as contradictory to the existence of the claim for reimbursement under Article 672 (1) of the Commercial Act, which is the subject matter of the lawsuit in this case.

Examining the records in accordance with the relevant legal principles, the lower court’s judgment is justifiable.

There is no error by misapprehending the legal principles as to the objective scope of res judicata.

2. With regard to the assertion of misunderstanding of legal principles as to the legal nature of joint and several liability borne by each insurer in double insurance, if there is a person liable for compensating for the loss caused by an accident caused by an non-insurance motor vehicle accident, the special agreement stipulating that the insurer compensates the insured for the loss in accordance with the terms and conditions of the contract (hereinafter “non-insurance special agreement”) is an accident insurance with the nature of the non-life insurance as well as the nature of the non-life insurance (see, e.g., Supreme Court Decisions 9Da50699, Feb. 11, 200; 2002Da61958, Dec. 26, 2003). In this case, Article 672(1) of the Commercial Act concerning non-life insurance is applicable mutatis mutandis to each insurer, and the insurer is jointly and severally liable between each insurer and each insurer.