He was convicted for the deadly 2019 arson attack at famed anime studio Kyoto Animation that killed 36 people and injured dozens.
That's according to Japan's public broadcaster NHK.
Shinji Aoba, now 45 years old, set the studio ablaze in 2019 by dousing the entrance area of the Kyoto-based studio, better known as KyoAni, with petrol - killing mostly young artists.
He himself suffered heavy burns and underwent intensive treatment for nearly a year.
Reports say Aoba held a grudge against the studio, known for the series "Violet Evergarden".
Aoba told police that he believed the studio had plagiarized his novel, an allegation KyoAni denies.
Prosecutors had demanded the death penalty for Aoba, while local media say his defense sought a lighter sentence or to have him acquitted due to "mental incompetence".
The arson attack sent shockwaves not only through Japan where violent crime is rare, but also through the studio's far-reaching overseas fan base, and prompted condolences from world leaders.
