KYOTO, Japan — He can’t get the women out of his mind.

A day after an apparent arson killed at least 34 people at an animation studio in the Japanese city of Kyoto, a neighbor, the 81-year-old Ken Okumura, remembered seeing several women jump from the building’s second floor. They were so badly burned that blood was coming from their noses, and all of their clothes but their underwear were gone.

“Just horrible,” Mr. Okumura said on Friday, as the smell of burning still hung in the humid air.

Much was still unknown about the Thursday fire, which appeared to be Japan’s worst mass killing in decades. The police identified Shinji Aoba, 41, as a suspect in the case, based on statements they said he made when he was apprehended. They said Mr. Aoba was being treated for severe burns and had not been arrested.

Japanese news reports, citing unnamed police sources, said the suspect had told the police that he started the fire because he believed the studio, Kyoto Animation, “stole a novel” from him.