Eight teenagers have been arrested in connection with the fatal beating early Tuesday of a 15-year-old boy at a park in Kasukabe, Saitama Prefecture.
Takahiro Hoshino, a first-year student at Kasukabe Evening High School, suffered a ruptured liver and died from internal bleeding, according to a police autopsy.
Police said seven of the eight suspects, including a 16-year-old girl, were Hoshino's schoolmates. The other suspect, a 16-year-old boy, works at a local company.
The suspects, aged 15 and 16, reportedly told investigators that Hoshino owed them money and they beat him up after he failed to pay them back.
Five of the suspects were arrested Wednesday, and the remaining three turned themselves in that night.
The suspects called Hoshino out Monday night, beating him for four hours starting at around 10:30 p.m., police said.
Hoshino was found Tuesday morning lying on the sports ground inside the park with a bloody nose.