A former Navy admiral, Black hand also known as Zephyr or master Z by his subordinates, has stolen the Dyna stones, a weapon of mass destruction that can rival the ancient weapons, and plans to use it to destroy all the end points which can cause great calamity throughout the sea.
On the other hand Luffy and his crew became entangled with Master Z, when they saw him floating in the ocean and chopper insisted to cure him. upon recovery, he thanked them. But after knowing that they were pirates he attacked and took Luff'y straw. Thus, the start of their battle with Master Z and uncovering the reason why he resigned as a Navy admiral and plans to destroy all pirates.
