WARNING: This article deals with extreme violence, suicide and mental health issues

When Kyota Hattori was arrested on suspicion of attempted murder aboard a Tokyo train on Oct. 31, he had an unsettling confession.

It was his intention, the 25-year-old allegedly told police, to stab a passenger to death, and he was fully aware of his actions when he subsequently set a train carriage ablaze using lighter fluid he had carried with him.