"Foreign investors now have no choice but to buy Japanese stocks, " said Kenichi Hirano, market analyst at Tachibana Securities.

WSJ: Tokyo Stocks Up as Investors Embrace Bank of Japan Easing Plan

"The upward pitch of the market, particularly since May 10, rang many alarm bells and frankly seemed to defy gravity, " said Kenichi Hirano, market adviser at Tachibana Securities.

WSJ: Japanese Stocks Fall Sharply

"The upward pitch of the market, particularly since May 10, rang many alarm bells and frankly seemed to defy gravity, " said Kenichi Hirano, a market adviser at Tachibana Securities.

WSJ: Japanese Stocks Fall Sharply