The global frenzy in AI has turned an obscure Japanese company into a stock-market star. Fujikura Ltd., which makes wire cabling for data centers, is the best performer on the Nikkei 225 Stock Average index, with its shares surging more than 400% this year. It will join the MSCI global standard indexes on Nov. 25 as the sole addition from Japan while eight other companies from the countryBloomberg Terminal will be removed....