TOKYO, April 30 (Reuters) - Japanese shares fell on Friday as lacklustre earnings reports and profit forecasts from technology firms, and a spike in domestic infections of the novel coronavirus weighed on investor sentiment.

The Nikkei 225 Index was down 0.46% at 28,920.24, as of 0200 GMT, while the broader Topix edged 0.07% lower to 1,907.67.

Japanese tech stocks led the declines as investors sifted through latest earnings reports and sold shares of companies that failed to live up to their lofty expectations for a robust rebound this year, analysts said

Investors are also growing more worried about COVID-19, because new infections in Tokyo and Osaka are rising even after the declaration of a state of emergency for the two cities at the start of this week, analysts said.

"The earnings coming in so far have not justified the massive rally in stocks from last year, so the upside is limited," said Ayako Sera, a market strategist at Sumitomo Mitsui Trust Bank.

"Britain and the United States have shown that vaccinations lead to a resumption of economic activity, but unfortunately Japan is lagging behind."

Z Holdings Corp fell 6.99% after the search engine operator and Internet advertiser's profit forecasts for the current fiscal year disappointed some investors who expected more benefits from its merger last month with Line, which is Japan's most popular messaging app.

Sony Group Corp lost 6.44% after the maker of the PlayStation gaming console said it expects profits to fall as stay-at-home demand wanes.

Murata Manufacturing Co also fell 3.79% after the electronic parts maker's forecasts also missed analysts' expectations.

One exception to the declines in the tech sector was CyberAgent Inc. Shares of the mobile phone game operator surged by 15.08% after the company raised its earnings forecasts.

(Reporting by Stanley White; editing by Uttaresh.V)