SoftBank Group Corp. will be the first Nvidia Corp. customer to build a supercomputer based on the chipmaker’s new Blackwell design, a move to meet growing demand in a country eager to catch up in artificial intelligence.SoftBank’s telecom unit plans to build Japan’s most powerful AI supercomputer to support a wide range of local services, the two companies said Wednesday. That computer will be based on Nvidia’s DGX B200 product, which combines computer processors with so-called AI accelerator c...