TOKYO, Dec 21 (Reuters) - Japanese equities jumped on Tuesday after two sessions of decline, with chip-related Tokyo Electron (8035.T) and Advantest leading the pack, as investors snapped up stocks that were dragged by concerns of the Omicron COVID-19 variant. The Nikkei share average (.N225) jumped 2% to 28,500.34 by 0225 GMT, while the broader Topix (.TOPX) advanced 1.7% to 1,974.20. "The Japanese market fell too much in the previous sessions because of an extreme caution for impact of the Omicron, which is affecting the U.S. and Europe," said Kazuharu Konishi, head of equities at Mitsubishi UFJ Kokusai Asset Management. "But Japan so far has not seen many infections. On top of that, Japanese shares are relatively cheap." The Nikkei has lost almost 4% in the past two sessions as the Omicron continued to stoke worries over an economic slowdown worldwide, while hawkish moves by global central banks curbed risk appetite. Heavyweight chip-related shares rose after Micron Technology (MU.O) beat market expectations by delivering stronger quarterly results. read more Tokyo Electron (8035.T) gained 3.74%, Advantest rose 4.31% and Shin-Etsu Chemical (4063.T) rose 2.11%. Drugmakers (.IPHAM.T) rose 1.99%, with Shionogi & Co (4507.T) jumping 6.82% after a local media report that preliminary studies suggested that its COVID-19 drug could work against Omicron infections. Shionogi"s peer, Daiichi Sankyo (4568.T), rose 3.57%, while Astellas Pharma (4503.T) slipped 0.22%. Sporting goods maker Asics (7936.T) jumped 4.53% after its U.S. peer Nike (NKE.N) reported robust earnings. read more There were 215 advancers on the Nikkei index against seven decliners. Z Holdings (4689.T), down 2.26%, lost the most on the Nikkei, followed by Mitsubishi Materials losing 1.08% and Shinsei Bank (8303.T) falling 0.93 %.