noun
pyromaniac; arsonist
Refers to a person with a compulsive urge to set fires. Often used in news reports and psychological contexts.
警察は放火魔を逮捕した。
The police arrested the pyromaniac.
その連続火災は放火魔の仕業とみられている。
The series of fires is believed to be the work of an arsonist.
放火犯 is a more formal/legal term for 'arsonist', focusing on the crime; 放火魔 emphasizes the psychological compulsion.
Compound of 放火 (ほうか, 'arson') and 魔 (ま, 'demon' or 'mania'), literally 'arson demon/maniac'.