Tokyo stocks soared as the yen weakened Friday morning, with the Nikkei 225 stock index topping 52,000 for the first time ever. The benchmark has been rallying all week in a run that has caught many investors off guard. It passed the 50,000 level for the first time on Monday, before gaining another 1,000 points two days later. On Friday morning, it rose as high as 52,391.45 at 9:50 a.m. while the yen weakened to nearly ¥154 against the dollar from about ¥152 on Thursday. The Bank of Japan kept