The suspected arsonist behind Thursday’s deadly blaze at the Kyoto Animation studio in Japan was “angry” and “discontented” with workers there — and allegedly shouting “about how he had been plagiarized” after setting the place on fire, a witness says.

“They faked it!” the 41-year-old man reportedly yelled in Japanese.

He had been planning the morning attack, with police pointing to a surveillance video that allegedly shows him filling up two 20-litre cans with gasoline, which were later found at the scene.

Local reports said the man, who has not been identified, was spotted walking aimlessly down a nearby road — staring into space — just two days before the fire.

Investigators believe he has no connection to the Kyoto Animation Co., despite his claims of plagiarism.

A woman who saw him being detained Thursday told reporters that he “seemed to be discontented.”

“He seemed to get angry, shouting something about how he had been plagiarized,” she said, according to Reuters.

The man allegedly shouted “Die!” before dousing the Tokyo studio — which produces “anime” TV and internet shows — with gasoline and setting it on fire. The blaze left 33 people dead and more than 35 injured, 10 critically.

Authorities said Thursday night that they were still investigating the circumstances surrounding what happened. They told reporters that the suspected arsonist has a driver’s license that lists a Tokyo address, but little else is known about him — or the victims.

“I imagine many of the people who died were in their twenties,” said Kozo Tsujii, a 71-year-old resident who drives by the studio every day on his commute.

“I’m just very, very sad that these people who are so much younger than me passed away so prematurely,” he told Reuters.

With Post wires