Holden Matthews, 22, switched his plea to “guilty” on Monday.
The alleged crime shows how the U.S.-based neo-Nazi terror group has an international presence.
“What don’t you understand?” the judge asked the boy.
Authorities are suspecting a possible arson attack at a three-story studio of Kyoto Animation Co.
Two were at a rabbi's house — and one at a nearby Jewish center.
Police said earlier this week that the fire was intentional.
The NAACP deemed the fires in Louisiana, plus another fire at a civil rights center in Tennessee, to be “domestic terrorism.”
The arsonist was tackled in a Starbucks by a mustached man in a Hawaiian shirt and a guy with a 2x4.
The FBI will be looking into his involvement in black metal music
"We saw other crimes were imminent," said Butch Browning, the Louisiana Fire Marshal.
The 37-year-old has now been sentenced to 20 months in prison.
He was allegedly trying to set a gas station on fire