"Takehaya" is a pirate. He is named after the Japanese God of Sea and Storms. His men took 6 crew members of the Nathan James.
In S3E3, it is revealed that he was formerly an officer of the Japanese Maritime Self-Defense Force (Japan's navy, in other words).
He went rogue after the plague hit Japan and the American cure proved ineffective and started his pirate career out of guilt that he somehow caused the death of his people by supplying a tainted cure (in reality Peng poisoned their blood prior, making the cure ineffective to them at that point).
As mentioned above, he is named after the Japanese God of Sea and Storms. Whether this is because of his former military experience or if his raids became so famous is yet to be known. His real name is revealed to be Kaito, but a last name is unknown. His wife is Kyoko.
His actions left many dead, including the Vietnamese and nine members of the Nathan James crew. Those killed at the party in Hai Phong, Vietnam include eight members of the Vietnamese security team, one Vietnamese civilian, and five members of the Nathan James's crew. PO1 G. Lincoln, Riley, Harris, and DaCunha were killed by Takehaya's pirates at the party by either shooting them or firing an RPG at the helicopter the Nathan James was using at the time. Lt (jg). Will Mason died of a gunshot he received in the altercation at the party after he was abducted with other crew members after the pirates pumped him dry of his blood. Another Nathan James crew member named Kudelski was killed by one of the mines Takehaya's men set. Three more members, Wallace, Butler and PO1 Javier Cruz were all shot in the neck and died during the attack on Takehaya's compound. His actions left many Americans, most notably the crew of the Nathan James and their families emotionally scarred through the videos they sent to the American government.
He partially redeemed himself by realizing that Peng Wu was the one truly responsible for his people's extermination and helped the Nathan James crew take him down. To this end he personally killed two Chinese MSS agents, helped the Nathan James escape Peng's Chinese Destroyers, even blowing one up with his mines and personally killed Peng with his pirate friends and the crew of the Nathan James backing him, saving millions of people from extermination as a result.
- Takehaya, who is referred to as the mythological Japanese Shinto god of Sea and Storms, actually has a longer name. The full name of the god is Takehaya Susano no Mikoto, but chances are Takehaya's men just call him "Takehaya" for simplicity.