The trial schedule for Takeshi Koizumi was set after prosecutors and his lawyers met for his pretrial proceedings on Wednesday.
Koizumi is charged with fatally stabbing former vice minister of health and welfare Takehiko Yamaguchi, 66, and his wife Michiko, 61, at their home in the city of Saitama last November, and also attempting to kill Yasuko Yoshihara, 73, wife of another former health and welfare minister, at their home in Tokyo in the same month.
The case will not be tried under Japan's lay judge system, introduced in May, as he was indicted in March after prosecutors claimed that he is mentally competent.