The Yamagata District Court sentenced a rightwing activist to eight years in prison Thursday for setting fire to the home of the mother of Liberal Democratic Party lawmaker Koichi Kato in Tsuruoka, Yamagata Prefecture, last year.

Masahiro Horigome, 66, a member of a Tokyo-based rightist group, was convicted of spreading gasoline in a bedroom of the house and setting fire to it with a lighter on the evening of Aug. 15, 2006.

Presiding Judge Takeshi Kaneko said, "The defendant's thinking is dangerous, and the crime, which challenged the freedom of speech and democracy, was vicious."

Prosecutors had demanded 12 years in prison, saying the crime was a challenge democracy by violent means. "Resorting to violence as a way to show one's objection to political speech cannot be tolerated," the prosecutors said.

The prosecutors argued that Horigome, facing numerous debts from gambling and suffering diabetes, became pessimistic over his future and this led him to try to die in a "heroic" way and make a name for himself among rightists.

They said he decided to target Kato after reading a magazine article in which Kato criticized then Prime Minister Junichiro Koizumi's repeated visits to Tokyo's war-linked Yasukuni Shrine.

The defense, meanwhile, argued that Horigome felt resentment against those who hinder the prime minister's visits to Yasukuni Shrine, and was merely trying to exercise the right to defend his country.