Police arrested a 15-year-old high school student Monday suspected of fatally stabbing another teenage boy who is believed to have been dating the alleged attacker's former girlfriend, in Saitama, north of Tokyo.
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 sometime around 11 p.m. Sunday.
The police believe the suspect may have been motivated by anger over his relationship with the girl. The police said he indicated that he carried out the attack.
The girl's older sister, who was in the apartment with her boyfriend at the time of the attack, notified the police.
The police later found the suspect at his home in the neighboring city of Misato.