The general shipping method used Japanese vehicles into Hong Kong is RORO (roll-on, roll-off) although the more expensive shipping method of containers can be arranged on request.
Cars and vehicles into Hong Kong do not require anything apart from the standard documentation required for exporting out of Japan.
Although there are no import taxes in importing into Hong Kong there are “first registration taxes” the first time the vehicle is registered. There are also stringent emissions regulations. For more details see this government link.