Kuaishou Technology, operator of China’s second-largest short video app, is developing a new international revenue stream with “not-safe-for-work” (NSFW) avatars, as Chinese artificial intelligence firms compete in the lucrative field of virtual companions. Kuaishou formally launched its AI companion service, FantaSay, through its Singapore unit, Symphony Tech, last month, after a trial run that began in February. The service promises an “ultimate immersive chat experience” with a “variety of...