In the first half of the Grand Line, the Kuja Pirates were the strongest pirate crew.
"Joining would be fine. There's no downside to it."
Becoming one of the Shichibukai had no real drawbacks. Although other pirates would see them as standing with the Marines and become hostile toward them, those pirates were actually envious as well...
If they were given the chance, they would definitely want to become Shichibukai too.
Of course, there were also people unwilling to become Shichibukai, such as Ace. Ace had made a name for himself soon after setting sail, and the Marines had invited him to become one of the Shichibukai.
No one knew whether Garp had anything to do with it, but Ace had refused to become a Shichibukai at the time.
"Since my husband says to join, then I'll become one of the Shichibukai. But I definitely won't obey Sengoku's summons."
Hancock said.
Becoming a Shichibukai granted considerable authority. They became legal pirates and no longer had to worry about being arrested by the Marines, but they had to give something in return as well.
For instance, if the Marines issued a summons, the Shichibukai had to answer it. They could not enjoy the benefits for free. The reason Sengoku had proposed establishing the Shichibukai was to make use of pirates' power.
"What are the Shichibukai?"
Nami asked curiously. She was very interested in the Shichibukai; they sounded incredibly formidable.
"The Shichibukai are seven powerful pirates officially recognized by the World Government. Only those with enough power to intimidate an entire nation can possibly receive an invitation. They become legal pirates."
Momousagi explained it to Nami.
"The power to intimidate a nation?" Nami suddenly felt that the Arlong Pirates were not much after all. At most, they only controlled a few villages.