Japanese police on Wednesday arrested the man suspected of killing 36 people at Kyoto Animation last July after he had spent 10 months recovering in two hospitals, media reported.
Police had issued an arrest warrant for Shinji Aoba at the time of the fire but had been unable to question him after he suffered serious, self-inflicted burns.
Public broadcaster NHK said that police arrested Aoba at a Kyoto hospital, where he confessed to the crimes, and that he was transferred to police headquarters for further questioning.
Police will brief media later on Wednesday, NHK said.
A spokesman at Kyoto Prefectural Police Headquarters said he could not confirm the arrest.
The fire had killed mostly young artists at the studio, shocked animation fans around the world, and prompted tributes from world leaders such as Canadian Prime Minister Justin Trudeau and Apple's chief executive, Tim Cook.
In a statement, Kyoto Animation said it expected the suspect to be prosecuted "to the maximum extent" under the law.
"We have no further words for the suspect... Our fallen colleagues will never return, and our wounds will never heal," it said.
Kyoto Animation is well known in Japan and abroad for its series and movies, including "Violet Evergarden", which has been on Netflix.
In mid-July last year, Aoba went to the studio, poured fuel around the entrance and shouted "Die!" as he set the building ablaze, media reported. After the attack, Aoba reportedly told police he had done it because the studio had plagiarized his novel.