In issuing the death sentence, chief judge Keisuke Masuda said Thursday that the defendant was “neither insane nor suffering from diminished mental capacity at the time of the crime.”

The man, Shinji Aoba, admitted in court last year to starting the fire but his lawyers argued that he was mentally unstable and was suffering from delusions during the attack. He had a psychological disorder had left him incapable of distinguishing between right and wrong, they said.

When the trial began in September, Aoba pleaded not guilty to five charges including murder, attempted murder and arson.

“I didn’t think so many people would die, and now I think I went too far,” Aoba told the Kyoto District Court at the time. His lawyers asked for him to be acquitted or given a lesser sentence.

But prosecutors said the severity of the crimes demanded the heaviest sentence possible.

“It is an unprecedented case of arson and mass murder, and the number of victims is by far the largest in the history of Japanese criminal trials,” the prosecution told the Kyoto District Court at the end of the trial.

Japan is one of the few developed countries to still retain death penalty, which is carried out by hanging.

Although there are 107 people on death row, Japan carried out no executions in 2023 for the first time in thee years. International human rights groups have repeatedly called for Japan to abolish the death penalty but a 2020 government poll showed that 80 percent of the public favor retaining it.

Aoba, who was 41 at the time, walked into the building owned by Kyoto Animation, one of Japan’s premier anime production houses, on July 18, 2019, and sprayed a flammable liquid around the office, screaming: “Die!,” police said at the time.

It appeared to set off secondary explosions, sparking panic as workers rushed into stairwells or up onto the three-story building’s roof.

Firefighters wrestled for hours with the blaze. In the end, 36 people died — many of them young animators — and left 32 more with serious burns and other injuries.

Aoba suffered severe burns to 90 percent of his body and had to undergo 12 operations.

The studio, Kyoto Animation, was founded in 1981 and is one of the country’s most important producers of anime, a Japanese-style of animated art that often features vibrant graphics and fantastical storytelling. Its notable titles include “Full Metal Panic!,” “K-On!” and “Sound! Euphonium.”