Japan's Nikkei 225 index soared past 40,000 points, marking a historic peak.

The rise is credited to robust tech sector earnings and optimism surrounding artificial intelligence.

However, there's apprehension about a possible investment bubble reminiscent of the 1990s dot-com era.

The Nikkei's performance is partly mirroring the U.S. Nasdaq's record highs and the success of chip stocks.

Strong corporate earnings are currently justifying the high stock valuations, mitigating bubble fears.

Key drivers for the index include corporate governance reforms, a weaker yen, and Japanese firms with strong international sales.

Analysts maintain a positive outlook, suggesting the Nikkei 225 remains undervalued despite reaching new heights.