Tokyo's benchmark Nikkei index closed lower Tuesday amid uncertainties from the domestic Covid-19 situation to the fate of the virus-plagued Tokyo Olympics. The Nikkei 225 index fell 0.19 percent, or 55.68 points, to 28,963.56, but the broader Topix index edged up 0.09 percent, or 1.80 points, to 1,962.65. si/kaf/reb