A Somali man accused of attempting to hijack a Bahamian-registered oil tanker off Oman in March 2011 — the final of the four men brought to Japan to be tried under the 2009 antipiracy law — pleaded not guilty Tuesday before the Tokyo District Court.

Just as in the previous trials of the other three men, the 21-year-old's case is being heard by three professional and six lay judges. The three other Somalis admitted to involvement in the attempted hijacking and were convicted by the lower court. Two so far have appealed.

This time, however, the defendant, whose name has been withheld because he was a minor at the time of the alleged crime, is challenging prosecutors' allegations. A ruling is set to be handed down April 12.