1st LD Writethru: Japan's key stock index plunges after ruling party election

TOKYO, Sept. 30 (Xinhua) -- Japan's benchmark Nikkei stock index, the 225-issue Nikkei Stock Average, plunged more than 4 percent on Monday after former Defense Minister Shigeru Ishiba was elected head of the ruling Liberal Democratic Party last Friday.

The sharp decline saw the index dive more than 4.6 percent at one point as Ishiba has shown a positive stance towards increasing taxes on financial income and co