An indefinite prison term sentence given to a 24-year-old man over a fatal random knife attack aboard a shinkansen in 2018 was finalized Tuesday after the ruling was not appealed.

The Odawara branch of the Yokohama District Court ruled last month that Ichiro Kojima murdered passenger Kotaro Umeda, 38, with a machete and a knife and severely wounded two women in their 20s on a bullet train en route from Tokyo Station to Shin-Osaka Station on June 9, 2018.

The deadline to appeal the ruling was on Monday.

Kojima, who admitted to the charges, said he committed the attack with the hope of spending the rest of his life behind bars.

Prosecutors, while acknowledging Kojima's "selfish desire" to spend his life in prison, sought an indefinite prison term for what they called "a brutal random killing."

His defense team had called for a more lenient sentence, saying he might repent if given the chance.

Kojima told the court he had tried to limit the number of fatalities to no more than two as he thought killing three people would result in the death penalty.

Kojima first attacked the women with the machete and knife. He then killed Umeda by slashing his neck and thigh when Umeda tried to intervene, according to the ruling.