Public prosecutors on Tuesday sought a 23-year prison term for Tomonobu Kojima, a senior member of a Philippines-based Japanese crime ring that allegedly masterminded a series of robbery and fraud cases across wide areas of Japan.

In their closing argument in a lay-judge trial at Tokyo District Court, the prosecutors said that the cases in which Kojima, 47, was involved by recruiting perpetrators served as the origin of a series of "tokuryu" crimes committed by loosely organized groups of anonymous members.

"The cases have led to many copycat crimes, and the defendant should be punished severely," the prosecutors stressed.