Public worries that the nation's youth are out of control were heightened by the recent killing of a four-year-old infant by a 12-year-old boy in the southern city of Nagasaki, the latest in a list of high-profile juvenile crimes.
The Nagasaki case came only days after the beating to death of a 13-year-old by fellow teens on the southern island of Okinawa.
Under Japan's Criminal Code, children under 14 cannot be prosecuted.
Suspects are instead transferred to child welfare centres, which then decide whether to refer the case to a family court.
Japan's juvenile arrests one-
tenth that of United States
Experts, however, say the media is distorting the real picture by focusing on data that seems to back up their assertions that today's juveniles are committing more violent crimes than their predecessors.
"Everyone says that youth crime is becoming more vicious, or that the incidence of crime is increasing rapidly," said lawyer Manabu Sunose.
"But if the mass media were to look at the data properly, they would realise this is not the case."
Police figures show those aged 14-19 arrested for murder in the first five months of this year rose to 52 from 18 in the same period last year.
But such short-term comparisons are misleading, Sunose said.
In fact, Japan's annual rate of juvenile arrests for murder is far lower than in the 1960s and has been stable in a range of roughly 80-120 for three decades.
That is about one-tenth of the figure in the United States, where the population is twice as big.