Japan declared on 21 December 2018 that it opposes Article 8 and Article 10(a) of the 1965 Hague Convention on The Service Abroad of Judicial and Extrajudicial Documents in Civil or Commercial Matters.

Reminder: Article 8 states that “Each Contracting State shall be free to effect service of judicial documents upon persons abroad, without application of any compulsion, directly through its diplomatic or consular agents. Any State may declare that it is opposed to such service within its territory, unless the document is to be served upon a national of the State in which the documents originate”.
Article 10 (a) states that “Provided the State of destination does not object, the present Convention shall not interfere with a) the freedom to send judicial documents, by postal channels, directly to persons abroad”.
Source: here