Chapter I General Provisions
Article 3 (Receipt of Requests and Sending of Evidence)
(1) A request for assistance shall be received, and evidence shall be forwarded to the requesting country, by the Minister of Foreign Affairs; except that the Minister of Justice shall carry out these tasks when a treaty confers the authority to receive requests for assistance on the Minister of Justice or when the Minister of Foreign Affairs gives consent in an emergency or under other special circumstances.
(2) When the Minister of Justice receives a request for assistance or forwards evidence to the requesting country pursuant to the proviso of the preceding paragraph, the Minister of Justice may ask the Minister of Foreign Affairs for cooperation necessary for the execution of matters relating to the assistance.
Article 4 (Measures to Be Taken by the Minister of Foreign Affairs)
Upon receiving a request for assistance, the Minister of Foreign Affairs shall, except where any of the following applies, send to the Minister of Justice the written request for assistance or a certification prepared by the Minister of Foreign Affairs of the fact that such a request has been made, as well as related documents, with the opinion of the Minister of Foreign Affairs attached:
(i) When a request has been made based on a treaty but the form of the request does not conform to the requirements of the treaty;
(ii) When a request has been made without being based on a treaty but there is no guarantee from the requesting country that it will honor requests of the same sort from Japan .
EDIT.