A 15-year-old high school student was arrested Monday on suspicion of fatally stabbing another teenage boy in Soka, Saitama Prefecture, who was thought to have been dating his former girlfriend.
Police allege the suspect, whose name is being withheld because he is a minor, killed Kosuke Nishiyama, 16, and seriously wounded Nishiyama's 16-year-old girlfriend at her apartment in the city sometime around 11 p.m. Sunday.
The police believe the suspect may have been angry about Nishiyama's relationship with the girl and said he indicated that he carried out the attack.
The girl's older sister, who was in the apartment at the time, notified the police, who later found the suspect at his home in the neighboring city of Misato.