Shachi is a member of the Heart Pirates and one of Law's closest crew members. He's pretty much a standard pirate—loyal to his captain, generally easy-going, and like his crewmate Penguin, he's openly interested in women. Beyond that, not much has been revealed about him.
What we do know is that Shachi wasn't always such a good guy. As a teenager, he was a bully who enjoyed mocking others and starting fights. He clearly had a thing for strength and respect, which makes sense given how he ended up joining Law's crew: Law beat him and Penguin up, and apparently that was impressive enough to make him want to follow the guy. Classic pirate logic.
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