The 19-year-old male who played a key role in the murder of a teenage boy on a Kawasaki riverbank last year was sentenced to nine to 13 years in prison Wednesday at the Yokohama District Court.

In handing down the so-called indeterminate sentence as stipulated under the Juvenile Law, presiding Judge Hiroko Kondo highlighted the cruelty of the assault that left 13-year-old Ryota Uemura dead. Uemura had been part of a group of friends that included the 19-year-old.

"The victim's neck was slashed more than once and he was forced to swim in the river in the middle of winter," Kondo said. "This was just so appalling — the cruelty (of the case) stands out."