(Restrictions on extradition)

Article 2.

(8) When a criminal prosecution for an offense committed by the fugitive other than the offense for which extradition is requested is pending in a Japanese court, or when the fugitive has been sentenced to punishment by a Japanese court for such an offense and the execution of the sentence of the fugitive has not been completed or the sentence has yet to be non-executable;

Article 89
Surrender of persons to the Court
4. If the person sought is being proceeded against or is serving a sentence in the requested State for a crime different from that for which surrender to the Court is sought, the requested State, after making its decision to grant the request, shall consult with the Court.

Article 97
Consultations
Where a State Party receives a request under this Part in relation to which it identifies
problems which may impede or prevent the execution of the request, that State shall consult with
the Court without delay in order to resolve the matter. Such problems may include, inter alia:
(a) Insufficient information to execute the request;
(b) In the case of a request for surrender, the fact that despite best efforts, the person
sought cannot be located or that the investigation conducted has determined that the person in the
requested State is clearly not the person named in the warrant; or
(c) The fact that execution of the request in its current form would require the
requested State to breach a pre-existing treaty obligation undertaken with respect to another State.