A successor in the main lawsuit is a person who has succeeded to the legal rights and obligations and the standing as a party of the party indicated in the title of execution. For a title of execution that is an ordinary judgment, it is a successor after the close of pleadings at the fact-finding instance; for a judgment without pleadings, it is a successor after the judgment is pronounced. If an heir who is a general successor renounces the inheritance and a seizure and assignment order is obtained after receiving a writ of execution for succession against that heir, the execution has been taken against a person who lacks standing as the execution debtor, so the effect of transferring the assigned claim to the assignee creditor does not arise. The scope of successors to whom res judicata extends is determined by the nature of the succession, not by whether the successor has any grounds for attack or defense. The forms of succession include causes such as juristic acts under private law, acts of execution such as assignment orders, inheritance, and subrogation by a person who has made performance. It also does not matter whether the succession occurs on the plaintiff's or the defendant's side.

For reference, the provision underlying the writ of execution for succession is Article 31 of the Civil Execution Act, which provides that a writ of execution may be issued for a successor of the creditor indicated in the judgment, or for execution against a successor of the debtor, only where the succession is evident to the court or is proven by a certificate. To start execution with a writ of execution for succession, under Article 39(2) of the same Act the writ of execution and a copy of the certificate must also be served in advance or at the same time, so mentioning this when writing about the requirements for commencement makes an answer solid. Also confirm that, where there are several heirs, each succeeds according to their share of the inheritance.