Goke, Body Snatcher from Hell (1968)

While a plane is being hijacked, a report of a bomb on board, another report of a UFO in the area is cut short as the hijacker shoots the radio and the controls. This while they encounter a UFO, causing them to crash on an uncharted island in the middle of nowhere. They soon find out there is an assassin on board. Panic ensues when it is discovered that there is a UFO on the island, taking them one by one , changing them.