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. Two women in their 20s, suffered minor injuries and are in a stable condition.
One of the injured women told the police Umeda had tried to stop the attacker when he began wielding a knife at her. The police seized a weapon when they arrested Kojima.
Kojima had two knives in his possession when he was apprehended.
Public broadcaster NHK reported that the suspect told police he felt "frustrated and wanted to kill someone".
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!"
The stabbings had occurred in the 12th carriage of the 16-car train service Nozomi 265, which runs between Tokyo and Shin-Osaka stations - considered to be one of the world's busiest train routes.
Some were carrying seat cushions to protect themselves.
"I was in a foul mood", police quoted him as saying.
According to the Kanagawa prefectural police and other sources, three passengers on the train were attacked.
There were about 880 passengers on board the train at the time of the incident. (JR Tokai) announced it would move up its plan to install more security cameras in bullet trains.