Japan's Prince hisahito reached a significant Milestone on Friday as he turned 18 becoming the first male royal family member to reach adulthood in nearly four decades this event highlights the challenges faced by the centuries old Imperial family which is grappling with a shrinking population and a system that only allows male succession to the throne hisahito who is set to become emperor one day is the nephew of Emperor Narito and the youngest of the 17 member Imperial family his stat as the last ER parent raises concerns about the future of the monarchy leading to ongoing debates about potential changes to the law to allow female succession or the adoption of male descendants from distant relatives