A 72-year-old man critically hurt in a recent knife and arson attack on a train in Tokyo has regained consciousness after being stabbed in the chest, investigative sources said Tuesday.

The man was allegedly stabbed after being sprayed in the face with pesticide by 25-year-old Kyota Hattori, who has been arrested on suspicion of attempted murder in the attack on a limited express train around 8 p.m. on Oct. 31.

The police plan to ask the man about the incident once his health improves, the sources said.

The knife-wielding Hattori, donning a costume reminiscent of Batman villain the Joker, allegedly poured lighter fluid inside the Keio Line train and set it on fire, leaving an additional 16 people with injuries including smoke inhalation.

The attack caused a panic at Kokuryo Station, where the train made an emergency stop, on Halloween night. Scenes of passengers escaping from the fire and crawling out of train windows were posted on social media.

Hattori was quoted as telling investigators, "I was not doing well at work or getting along with other people. I thought I would be given the death penalty if I killed two or more."

Hattori, who came to Tokyo around late September, was carrying a knife and a plastic bottle full of oil at the time of the incident.