By Agence France-Presse
The benchmark Nikkei 225 index lost 1.02 percent or 231.15 points to 22,461.89 in early trade, while the broader Topix index was down 0.94 percent or 16.44 points at 1,734.19.
The European Union slapped revenge tariffs on iconic US products including bourbon, jeans and motorcycles on Friday in its opening salvo in a trade war with President Donald Trump.
Global stock markets fell Thursday hours before the EU tariffs took effect, with the Dow Jones down for an eighth straight session, closing lower by 0.8 percent at 24,461.70.
"Japanese shares are seen dominated by sales following declines in bourses in Europe and in the US," SBI Securities said in a commentary.
With the yen also edging higher, traders are likely to sell shares to square their positions going into the weekend, added SBI.
The dollar slipped to 109.94 yen in early Asian trade from 110.36 yen in New York late Thursday.
In Tokyo, automakers were trading lower after luxury German carmaker Daimler cut its profit forecasts for 2018, blaming new tariffs on cars exported from the United States to China.
Honda dropped 2.11 percent to 3,337 yen, Toyota fell 1.69 percent to 7,271 yen and Nissan lost 0.64 percent to 1,022 yen.
Steelmakers were also lower -- despite an announcement of a partial exemption for Japanese-made steel products from US tariffs earlier this week -- with JFE dropping 1.68 percent to 2,096 yen and Nippon Steel down 0.91 percent at 2,146 yen.