He was initially arrested on attempted murder charges, which would be switched to murder charges when his case goes to the public prosecutor's office.
What appear to be fleeing passengers' belongings are strewn on the floor of a shinkansen auto next to the one where a knife-yielding man killed a male passenger and injured two women on June 9, 2018.
According to police, shortly after the departure of 22-year-old Ichiro kojima, a native of the city of Okazaki in Aichi Prefecture, was attacked with a knife on passengers.
In the clearest sign that the stabbings were random and indiscriminate, Kojima reportedly told police: "I was feeling frustrated - anyone would do".
Two women in their twenties sustained non-life threatening injuries, police said.
According to the Kanagawa Prefectural Police, Kojima started by allegedly attacking the woman sitting next to him, before proceeding to attack a woman on the other side of the aisle. "We would like to be left alone for now".
Kojima had two knives in his possession when he was apprehended.
Witnesses spoke of 20 to 30 passengers panicking and fleeing from the direction of the No. 12 vehicle.
Afterward, witnesses said some of the passengers were crying as they fled to the other coaches, shouting "Just keep going ahead", and "He has a knife!" Some were holding removed seats, apparently to protect themselves.
"I have been always anxious about him", his grandmother said in a telephone interview early Sunday.
After he started living with his grandmother, she said he mainly stayed home, reading books and surfing the internet.
In 2015, a man set himself ablaze on board a moving bullet train, killing himself and a woman in an unprecedented incident. The train was carrying more than 800 passengers at the time of the incident.
According to JR Central, an average of 446,000 passengers used Tokaido Shinkansen trains each day in fiscal 2015.