The Nikkei 225 index lost 2.11 percent or 453.83 points to 21,087.16. Over the week, the benchmark index fell 2.64 percent.

The broader Topix index on Friday shed 2.16 percent or 33.89 points to 1,533.46 yen for a drop of 2.42 percent on week.

After Tokyo closed on Thursday, US President Donald Trump's new tariffs on China sent a shockwave through global markets.

Trump's decision to impose tariffs on another $300 billion in Chinese goods aborted an equity market rally following the Federal Reserve's decision Wednesday to cut interest rates for the first time in more than a decade.

The dollar tumbled against the yen, a negative development for Japanese exporters.

"The Tokyo market plunged as its initial reaction to the surprise tweet, and then investors shunned buying ahead of the weekend," said Seiichi Suzuki, senior market analyst at Tokai Tokyo Research Institute.

But Suzuki added "not many investors believe the market will continue to plunge next week" considering stock prices eventually bounced back after earlier rounds of US tariffs on Chinese products and sanctions on Chinese tech giant Huawei.

Some investors will be looking for opportunities to buy on dips while the market digests negative news, he said.

The dollar fell to 107.02 yen from the 108-yen range seen when Tokyo closed on Thursday.

Toyota was down more than three percent when it announced downward revisions in full-year earnings but trimmed losses to 2.29 percent to close at 6,929 yen.

"The market was not worried over the downgrading too much" as it was largely because the company is bracing for a stronger yen, Suzuki said, noting Toyota's businesses remain solid.

Honda fell 4.02 percent to 2,613 yen just before it announced that its first-quarter net profit fell by nearly 30 percent due to heavier costs, lower sales revenue and a less profitable model mix, as well as a negative foreign exchange impact.