TOKYO, April 22 : J.P. Morgan on Wednesday raised its year-end target for Japan's Nikkei share average index to 70,000 from a previous target of 61,000, citing a boom in artificial intelligence and a weaker yen. J.P. Morgan also hiked its year-end target for the broader Topix index to 4,300 from 4,100. "Although some think the Nikkei 225 is overheated, rising to record highs while crude oil prices remain elevated, we think the Japanese equity market's longer-term growth potential has increased