As of 02:11 GMT, the Nikkei 225 index is trading down 6.04% at 31,740, recovering from an earlier drop to an 18-month low of 30,629.50.
Due to sharp price fluctuations, the Osaka Stock Exchange temporarily imposed restrictions on trading futures on government securities.
Hong Kong's Hang Seng Index is trading down 9.38% at 20,740, while Shanghai's SSE Composite Index fell by 6.04% to 3,140.11.
Analysts attribute the fall in the indices to the introduction of tariffs by the United States and retaliatory tariffs from China. Trump also signed an order imposing 25% tariffs on imports of passenger cars, light trucks and auto parts from April 3, saying the measure was necessary to protect "national security."