The 1,590 minors arrested for heinous crimes like murder, robbery and arson in the first nine months of this year is more than the total for 1996, police said Oct. 23.The figure for all of last year was 1,496. Robbery cases, including those in the category "oyaji-gari" (which literally means "hunt for middle-aged men"), are more than 50 percent from the same period last year, according to the latest statistics by the National Police Agency.The figures also include the high-profile case of a 15-year-old Kobe boy who was sent to a juvenile medical facility in suburban Tokyo this week for killing two small children and injuring three others between February and May. NPA officials said they plan to step up efforts against juvenile crime and cooperate with school authorities to beef up supervision of delinquent children.Of the 1,590 people age 14 to 19 who were arrested over heinous crimes from January to September, 1,044 were involved in robbery, up 54.2 percent from the same period last year, while 311 were held in sexual assaults against women, up 81.9 percent. High school students accounted for 349, up 55 percent, the NPA officials said.