The Tokyo Stock Exchange's top market saw a huge net growth in purchases by overseas investors in April. That helped drive a strong month for the segment overall.
Foreign-based investors bought 2.2 trillion yen, or over 16 billion dollars, more than they sold on the TSE's Prime market last month.
It was the first time since October 2017 that net foreign purchases on the TSE's top-tier segment exceeded 2 trillion yen.
Tokyo shares posted strong gains on the whole last month, with the Nikkei average rising for eight straight trading days at one point. It came as worries about financial turmoil in the US and Europe were somewhat eased.
Market players say a slight depreciation of the yen also helped lift export-related shares last month.
But they add that concerns about the management of American banks linger, and it's unclear how long foreign investors will continue buying Japanese shares.