TOKYO—Two big names in Japanese electronics and autos are joining forces to produce an electric vehicle together. Sony Group Corp. and Honda Motor Co. agreed to set up a joint venture this year to start selling an electric vehicle by 2025, both sides said Friday. The plan is to bring together Honda’s expertise in mobility development, technology, and sales with Sony’s imaging, telecommunication, network, and entertainment expertise. A union of traditionally different manufacturing businesses is uncommon for Japan. But it makes sense in the age of electric vehicles, which lack gasoline-powered engines and have complicated electronics. All the world’s automakers have been developing zero-emissions electric vehicles. But they face tough competition from relative newcomers like Tesla. The joint venture will develop and design the product, but will use Honda’s plant for manufacturing. Sony will develop the mobility services platform. Honda makes the CR-V sport utility vehicle and Clarity plug-in hybrid …