Chapter II Cooperation with the International Criminal Court
Section 3 Surrender of an Offender Sought for Surrender, etc.
Subsection 1 Surrender of an Offender Sought for Surrender
(Requirements for the Surrender of an Offender Sought for Surrender)
Article 19 (1) (i) when the case connected with the offense underlying the surrender request is pending before a Japanese court; provided, however, that this shall not apply where the ICC has determined that the case is admissible pursuant to the provisions of article 17, paragraph 1 of the Statute or has commenced proceedings in the case;
Admissibility challenge - State investigation or prosecution
EDIT.