If 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.
訴訟の目的が共同訴訟人の全員について合一にのみ確定すべき場合には、その一人の訴訟行為は、全員の利益においてのみその効力を生ずる。
In 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.
前項に規定する場合には、共同訴訟人の一人に対する相手方の訴訟行為は、全員に対してその効力を生ずる。
In 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.
第一項に規定する場合において、共同訴訟人の一人について訴訟手続の中断又は中止の原因があるときは、その中断又は中止は、全員についてその効力を生ずる。
The 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.
Read this with the articles around it