Fujikura Ltd., a Japanese wire and fiber optic cable maker, has emerged as the top performer on the Nikkei 225 this year, with its shares surging over 400%. Riding the global AI wave, the company will join the MSCI global standard indexes as the sole addition from Japan. Fujikura’s products are essential for AI infrastructure, including data centers and communications networks, which will require $1 trillion in spending. Analysts favor Fujikura, but some see greater potential in its competitors.