Except as otherwise provided for in this Code, capacity as a party, the capacity to sue or be sued, and the statutory representation of a person lacking the capacity to sue or be sued are governed by the Civil Code (Act No. 89 of 1896) and other laws and regulations. The same applies to the delegation of the powers necessary for performing procedural acts.

An association or foundation that is not a corporation and that has a designated representative or administrator may sue or be sued in the name of that representative or administrator.

①Persons with a common interest that do not fall under the provisions of the preceding Article may appoint one or more persons from among themselves to act as the plaintiff or defendant on behalf of all.

②If a person is appointed to act as the plaintiff or defendant pursuant to the provisions of the preceding paragraph after litigation has become pending before the court, any plaintiff other than a person selected to act as plaintiff or any defendant other than a person selected to act as defendant is automatically withdrawn from the litigation.

③A person that shares a common interest with the plaintiff or defendant in pending litigation but that is not a party to the litigation may appoint them to also act as the plaintiff or defendant on their behalf.

④A first person that has appointed a second person to act as plaintiff or defendant pursuant to the provisions of paragraph (1) or the preceding paragraph (the first person is referred to below as an "appointing party") may void their appointment or change the person they have appointed to act as a party to the case ( the second person is referred to below as a "appointed party").

⑤If an appointed party dies, or due to other reasons loses that status, another appointed party may perform procedural acts on behalf of all.

A minor or an adult ward may not perform any procedural act except through a legal representative; provided, however, that this does not apply if the minor may perform juridical acts independently.

①A person under curatorship, a person under assistantship (limited to a person that is required to obtain consent from the assistant to perform procedural acts; the same applies in the following paragraph and Article 40, paragraph (4)), or a guardian or other such legal representative is not required to obtain consent or a delegation of powers from the curator or curatorship supervisor, assistant or assistantship supervisor, or guardianship supervisor in order to perform a procedural act with regard to an action or appeal filed by an adverse party.

②A person under curatorship, a person under assistantship, or a guardian or other such legal representative must have a special delegation of powers in order to perform any of the following procedural acts:

Even if a foreign national does not have the capacity to sue or be sued pursuant to the laws of their home country, they are deemed to have the capacity to sue or be sued if they have that capacity pursuant to Japanese law.

①If a person lacks the capacity to sue or be sued, authority to act as a person legal representative, or delegation of powers that is necessary for performing a procedural act, the court must order this to be corrected within a specified time frame. In such a case, if there is a risk of damage arising from a delay, the court may have the person perform procedural acts on a temporary basis.

②A procedural act performed by a person without the capacity to sue or be sued, the authority to act as a person's legal representative, or the delegation of powers that is necessary for performing that procedural act, becomes valid retroactive to the time of the act through ratification by a party or legal representative that has come to satisfy these requirements.

③The provisions of the preceding two paragraphs apply mutatis mutandis if an appointed party performs procedural acts.

①If there is no legal representative or if a legal representative is unable to exercise the authority to act as a person's legal representative, a person seeking to perform a procedural act against a minor or adult ward may request the presiding judge of the court in charge of the case to appoint a special representative, by making a prima facie showing of the risk that the person will incur damage if there is a delay.

②The court may replace a special representative at any time.

③In order to perform procedural acts, a special representative must have the same delegation of powers as a guardian.

①The lapse of authority to act as a person's legal representative does not become valid until the principal or the agent notifies the adverse party of it.

②The provisions of the preceding paragraph apply mutatis mutandis to the voidance of a person's appointment as an appointed party or a change of appointed parties.

In this Code, the provisions concerning legal representatives and statutory representation apply mutatis mutandis to the representative of a corporation and to the representative or administrator of an association or foundation that is not a corporation but can sue or be sued in its own name.

If rights or obligations that are the subject matter of litigation are common to two or more persons or are based on the same factual or statutory causes, these persons may sue or be sued as co-litigants. The same applies if rights or obligations that are the subject matter of litigation are of the same kind and based on the same kind of factual or statutory causes.

A procedural act performed by one of the co-litigants, a procedural act performed against one of the co-litigants by the adverse party, and any matter arising with regard to one of the co-litigants does not affect any other co-litigant.

①If the subject matter of litigation is to be determined for all co-litigants only as a unified matter, procedural acts performed by one of them become valid only in the interests of all of the co-litigants.

②In a case prescribed in the preceding paragraph, procedural acts performed against one of the co-litigants by the adverse party are valid against all of them.

③In a case prescribed in paragraph (1), if there are grounds for a continuance or suspension of litigation proceedings with regard to one of the co-litigants, the continuance or suspension is valid against all of them.

④The provisions of Article 32, paragraph (1) apply mutatis mutandis, in the case prescribed in paragraph (1), to procedural acts that a co-litigant who is a person under curatorship or person under assistantship, or a guardian or other legal representative is required to perform in an appeal filed by one of the co-litigants.

①If a right that is the subject matter of litigation for one codefendant and a right that is the subject matter of litigation for another codefendant cannot legally coexist and the plaintiff requests it, the court must hear oral arguments and reach a judicial decision without instituting separate litigation.

②The plaintiff must make the request referred to in the preceding paragraph by the time of conclusion of oral arguments in the second instance.

③In a case as referred to in paragraph (1), if cases under appeal that each have a codefendant are pending separately before the same court of second instance, the court must hear oral arguments and reach a judicial decision after consolidating them.

A third party with an interest in the outcome of litigation may intervene in the litigation in order to assist either party.

①An application for supporting intervention must clarify the purpose and the grounds for the intervention, and must be filed with the court where procedural acts in that supporting intervention are required to be performed.

②An application for supporting intervention may be filed in conjunction with the performance of a procedural act that may be performed by a supporting intervener.

①If a party objects to a supporting intervention, the court reaches a judicial decision, in the form of a ruling, on whether or not to permit the supporting intervention. In such a case, the supporting intervener must make a prima facie showing of the reasons for the intervention.

②After having presented oral arguments or entered a statement in preparatory proceedings without having raised the objection referred to in the preceding paragraph, a party may not then raise such an objection.

③An immediate appeal may be filed against a judicial decision as referred to in paragraph (1).