The man accused of killing 36 people in an arson attack four years ago on Kyoto Animation has admitted to his role in the incident. But his lawyers entered a not-guilty plea, arguing he cannot be held criminally responsible because of a mental disorder.

Aoba Shinji appeared in the courtroom in a wheelchair. The 45-year-old defendant confirmed the facts in the indictment, saying at the time, he had no choice but to carry out the act. Aoba added he did not expect so many people to die.

The attack on the Kyoto Animation studio in 2019 is one of the country's deadliest arson attacks. It left 36 employees dead and 32 injured.
Aoba is accused of intentionally dousing the studio with gasoline that fueled the inferno. He faces multiple charges, including murder and arson.

Hundreds of people lined up outside the courtroom Tuesday hoping to watch the proceedings firsthand.

Aoba's defense is claiming he has a mental disorder that renders him incapable of distinguishing between right and wrong.

Prosecutors are arguing the crime was based on Aoba's "misdirected grudge". They say the defendant believed the studio was responsible for why his life wasn't going well after a novel he had written was rejected.

Prosecutors also say Aoba went to Omiya Station one month before the Kyoto incident, intending to indiscriminately murder people but ultimately abandoned the idea.

Former judge Wada Makoto says attention is now focused on what Aoba will say when he takes the stand on Thursday.

Professor Wada Makoto of Kansai University Graduate School of Law said, "It is important for society to clarify why something like this could happen, including the defendant's mental state, in order to learn lessons from this incident."

In future proceedings, the court will also hear witness testimony from doctors who evaluated the defendant's mental state.