A drifter who admired the Joker character from Batman and dressed as him to carry out a Halloween attack on a Tokyo train "wanted to kill lots of people" and planned his moves over months, buying a knife to use from the internet, police and media said on Tuesday.

The stabbing and arson attack, which briefly sent fire flaring in a train carriage, was carried out on Sunday night as many party-goers headed into Tokyo for Halloween celebrations and sent passengers screaming down the aisles of train carriages and scrambling out of windows to escape...