Throughout their many travels in the Grand Line and New World, the Heatwave Pirates have met up with many individuals that have assissted them on their adventure, whether they are temporarily or pemanently members of the crew.
Involvement With the Heatwave Pirates
Iwao was Riku's superior at the Corona Restraunt on Solaris. He was secretly a spy from the Revolutionaries who was ivestigating the claims of a Marine attack on Solaris, and that their leader was also an undercover spy from the Marines named Vice Admiral Johanson. When this information turned out to be true, Akihiko fought Johanson, but was killed in the fight. To carry out his dying wish, Raiken and Riku teamed up to defeat Johanson, with Riku joining Raiken's crew as a result.
Riku's younger sister who possessed Devil Fruit powers like her sister. She had the Paramecia-type Devil Fruit Agaru Agaru no Mi, the ability to rise and manipulate dead corpses. She was tasked by Akihiko with dealing with traitorous citizens who were supplying Marines with materials for the attack. She ended up captured by Johanson's right hand man, Rear Admiral Cerberus, who was masquerading as Ostanius. Arisu was tortured by him until Miyazaki broke her out and defeated Cerberus. She was offered to join Raiken's crew, but sjhe turned it down as she was dedicated to rebuilding Solaris.
Aiko and Kenji Nagarai
Inuzaka's parents who were the commanders of the Strikeforce, a secret underground special forces unit operating in the North Blue under the Marines' command. They were originally allies of the Heatwave Pirates when they arrived at Mirejois, allowing them to become the town's temporary authority while they supplied up for the Grand Line. While they appeared to be helping them take out multiple agents of Strikeforce, they were really doing in to protect themselves. When the crew, and Inuzaka, found out about the couple's true intentions, they planned to destroy the town and everyone in it to prevent the secret from getting out. The Heatwave Pirates and Inuzaka prevented the destruction and gave chase to the Nagarai's, who were leaving on a private ship. Raiken managed to defeat Kenji as Inuzaka and Miyazaki managed to defeat Aiko.
The town's news reporter. He always suspected the Nagarai's of nefarious intentions, but no one ever believed him because they always seemed to be viewed by everyone in a positive light. He was an ally of the Heatwave Pirates from the very beginning, offering them inside info on the Nagarai's. When the Nagarai's planned to destroy Mirejois, he teamed up with the Heatwave Pirates and Inuzaka, defeating nearly all of the Strikeforce underlings.
Ikatski's mentor and close friend. Arata taught everything he knows about being a sniper to Ikatski and greeted the Heatwave Pirates with kindness upon their arrival. He helped them sabatoge Kyon's assets on Solari Island in order to get him to leave. When this failed, Kyon caught on to him and ordered nearby Marines to capture and execute Arata. The Heatwave Pirates prevented this and went after Kyon while Arata escaped the island.
Kure S. Akira
Raiken's fellow Goshin. He had heard about him throughout his adventure and dreamed to once be a great pirate like him. When Raiken defected to the World Government, he advised his crew to seek out Akira's crew and forge an alliance with them, which Miyazaki did. Akira and Raiken met for the first time when the Marines attacked the Celestial Summit, where the two face off against each other. After Raiken turned on the Marines, he teamed up with Raiken to take down the Marines.
The Heatwave Pirates have also met other crews throughout all of their trials and tribulations. These crews have helped them in some way, whether it be small or large.
Involvement With the Heatwave Pirates
Great Dragon Pirates
The Heatwave Pirates were advised by Raiken to meet up with this crew and ally with them to help them gain an advantage in their inevitable showdown with the Marines. Miyazaki did just this and forged an alliance with them. Raiken respects Akira as a, "legend," and considers it an honor to stand by him in battle.
Demon Eye Pirates
Miyazaki also forged an alliance with Riku and his crew as part of Raiken's speech to them. Raiken also respects Riku as much as he does Akira.
Pegasus Wings Pirates
The Heatwave Pirates and Pegasus Wings Pirates wanted to prove to each other who was the superior crew. To do so, they agreed to a battle much like the one the Great Dragon Pirates and Demon Eye Pirates had. Their Divisions Commanders met up on a deserted island and engaged in a long battle that ended in a tie. With this, the crew has a deep rooted respect for the Pegasus Wings Pirates, and are considered to be the Heatwave Pirates' strongest ally, much like the alliance between the Great Dragon and Demon Eye Pirates
Free World Pirates
Much like the Pegasus Wings Pirates, the Free World Pirates wanted to duel the Heatwave Pirates to show who is superior. When the battle end, Raiken and Aiden left with nothing but respect for each other's crews.