Japan's Nikkei closes -2% and has entered correction territory, which is a fall of 10% or more from a recent peak.
The drop follows weakness on Wall Street on Friday and disappointing Chinese PMI data, and comes amid a strengthening yen but despite decent corporate earnings reports.
"It's important to note that fundamentals are not driving Japanese stocks lower — it's the fault of the weak overall investing environment," says asset manager Yoshihiro Okumura. "With valuations now steeply discounted and the market nearing its 200-day moving average, here would be a good place to buy."
Elsewhere in Asia, India's Sensex is -1.2%, while China and Hong Kong are closed for the Lunar New Year.