Sao

Sao is an infamous warrior from Poko Summit, Simo Island. He is prominently known and feared (especially in North-eastern Simo), where he lives in a deep cave and will kill anyone that he finds in, around or directly outside of the cave for unknown reason. He was and remains to be known as the most powerful warrior from Simo to ever live, with his power and abilities extending that of any of the Prime Overseers in the island's history. Because of this, the island government doesn't really know how to control, capture, or exile him, so they just warn people of the summit area.

Sao is also known to have been very close to Token at one point, up until he disbanded from Simo. Around that same time, Sao fled his village and began hiding out in the summit caves.

End of Earth Arc
During the End of Earth arc, Chris, Falgo and Lardface search for Sao in order to extract information about Token's much-unknown but definite involvement with Luger before his disbanding. Upon finding him, they end up having to fight him and nearly die, having to be rushed back to Lua Island by Maroon via helicopter, though they eventually healed, Maroon had to deal with attacks from Lab Co. at the Valentine homestead whilst helping Chris and Falgo recover.