A 16-year-old boy was arrested early Saturday on suspicion of killing a female classmate who was found stabbed to death in her apartment in Machida, western Tokyo, police officials said.
The boy, whose name is being withheld because he is a minor, has admitted to killing 15-year-old Yua Koyama, the officials said.
Asked about his motive, he allegedly told investigators that although he and Koyama had been classmates during elementary and junior high school, Koyama started treating him "coldly" after they entered high school in April.
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