In Japan the hot springs is one of the most traditional forms for relax that use Japanese society.
Normally the hot springs, in Japanese called Onsen温泉are shared but separate for men and women. But there are some private Onsen in which you can rent for a few hours a room with your own Jakuzzi that uses the hot springs of the area where it is located. This type of private hot springs is called Kashikirionsen貸切り温泉.
Besides enjoying the privacy of heat from the water, also the spectacular scenery contributes to an unforgettable and truly Japanese experience.