The Nikkei 225 fell 0.6% in early trading to 64,759.80 points, primarily due to escalating concerns about a war in Iran and rising energy costs. Construction and retail stocks led the decline, with Taisei dropping 4.9% and Ryohin Keikaku falling 2.4%. Brent crude prices surpassed $100 per barrel for the first time since July, and investors are closely monitoring the situation in the Middle East and oil price movements.