|Our creator had a thought. Wouldn't it be interesting if there were more kinds of people in the world? The same goes for the Subjects of Ymir, who can turn into Titans. All of us exist because someone meant for us to exist.|
|— Onyankopon's views on different ethnicities|
Onyankopon (オニャンコポン?) is one of the Anti-Marleyan Volunteers and aids the Survey Corps during the Raid on Liberio. He pilots an airship following orders from Hange Zoë for the Corps to use during their retreat.
Onyankopon is a dark-skinned man with black hair styled in a short crew cut. He appears to be well-built, as seen by his large arms and shoulders. He wears a military uniform of Marleyan issue with two black stripes going down the torso.
Onyankopon's casual clothes consist of a dark jacket over a dress shirt, and long pants.
Onyankopon comes off as a friendly man, easily building a rapport with Hange Zoë and other members of the Survey Corps during his dealings with them. However, he also seems to have a rather serious mindset, becoming slightly perplexed by some soldiers' fixation on trivial matters during their preparations, and praising Hange for easily adapting to the technologies and ideas being introduced to Paradis Island.
Onyankopon appears to be a religious man, professing to the Eldians on Paradis who question him about his skin color that he believes God created different ethnicities of people out of a desire to make the world "interesting."
When Onyankopon's home country was taken over by Marley, he was one of many who forcibly conscripted into the Marleyan army to serve as a soldier.
In 851, Onyankopon is among the first survey fleet sent by Marley to Paradis Island after the operation to retrieve the Founding Titan failed. His ship is captured and beached by Eren Yeager, where he and his fellow soldiers are confronted by Hange Zoë, offering to negotiate with them. When his commanding officer refuses to listen, Onyankopon joins his fellow crew member Yelena in disarming their commanding officers and accepting Hange's offer.
Meeting with Hange and Levi Ackerman, Onyankopon and Yelena allow the two to inspect their weapons, explaining that Marley has not yet launched a full assault on Paradis Island due to a war they are currently caught in. Hange guesses that they are sleeper agents who have infiltrated the Marleyan army, but Yelena explains to her that they are simply conscripted soldiers who have chosen to rally around Zeke Yeager in opposition of Marley as the Anti-Marleyan Volunteers.
Forming an alliance with Paradis Island, Onyankopon and his comrades begin sharing their technology with the islanders, with Onyankopon focusing on ways to strategically prepare Paradis Island for reintegration with the outside world, such as building ports for ships to dock.
In 854, during the Survey Corps' invasion of Liberio, Onyankopon participates in the retreat of the regiment's troops, serving as an airship pilot and picking up Armin first after his destruction of the Marleyan harbor. He follows the lights set up around the internment zone that function as a path for their escape, reassuring Hange of his piloting capabilities. He is left to pilot the airship as Hange leaves to speak with Zeke Yeager.
After returning to Paradis, Onyankopon and his fellow Volunteers turn over a stock of Titan serums they managed to steal from Marley to the Garrison. After receiving the serums, Dot Pixis has his soldiers capture the Volunteers, revealing that Paradis is not yet willing to trust Zeke and his followers.
While he is being held in captivity, Onyankopon is visited by Hange. Onyankopon makes no effort to conceal his dismay at the Paradis military for imprisoning the Volunteers, reminding Hange of all that the two forces accomplished while working together over the past three years. Hange is similarly unhappy with the predicament, but justifies the military's actions by revealing, to Onyankopon's shock, that Yelena had secretly met with Eren prior to his surprise attack on Liberio. Hange asks Onyankopon for any information he might have about Yelena, and Onyankopon reveals that Yelena was always the Volunteer who would step forward to execute any Marleyan soldiers that might suspect them of treason. Hange notes a seeming discrepancy in Yelena's behavior, pointing out that Yelena also campaigned passionately for Paradis's Marleyan prisoners of war to be treated fairly, which Onyankopon suggests may have been an attempt on her part to atone for her harsh behavior previously. Hange is unconvinced, and orders that Onyankopon accompany her to look into the matter further.
After Darius Zackly and other military officials are killed in a bombing at the military's headquarters, Onyankopon accompanies Hange to a hearing with the remaining commanders to discuss the attack. Hange provides the Volunteers with an alibi for the bombing, pointing out that Onyankopon was with her and that the other Volunteers were under house arrest at the time.
After another hearing is held to discuss the rogue faction of soldiers being led by Eren, Onyankopon accompanies Hange and the other Survey Corps officers as they visit Niccolo to question him. While they are waiting to speak with him, they discover Niccolo threatening and attempting to kill the two Warrior Candidates that were brought to Paradis, and are forced to defuse the situation. During the confrontation, it is discovered that the wine Niccolo and other Marleyan prisoners have been serving to the military's officials may have been spiked with Zeke's spinal fluid on Yelena's orders. Although Yelena's involvement immediately causes the soldiers to become suspicious of Onyankopon as well, he insists that he had no knowledge of the plan. Hange orders Onyankopon to inform Armin Arlert and Mikasa Ackerman of the news, but as he goes to get them he is captured by the Yeagerists, who have arrived at the restaurant. He and the rest of the Survey Corps members at the restaurant are then taken hostage.
The entire group, with the exception of Onyankopon, is placed in a cell in the military's Shiganshina headquarters. Onyankopon accompanies Yelena to visit them, revealing that he is still loyal to the Anti-Marleyan Volunteers in the process. Tensions are high between the prisoners and Onyankopon, and when Jean Kirstein tries to deduce what their true intentions are with Paradis, Onyankopon unhappily reminds the prisoners that the volunteers were the ones who helped "civilize" the island. When Griez interrupts their conversation to insult Niccolo, Onyankopon is horrified to see Yelena shoot him in the head. He then assists in removing Griez's corpse from the hall as Yelena continues to explain Zeke's intentions to the prisoners. Soon after, a Yeagerist arrives informing them of Infiltrators. He accompanies Yelena to the roof where a captured Pieck claims she will point out her own allies. However, Pieck identifies Eren as the enemy. The rooftop soon cracks with the Jaw Titan appearing in front of them. Onyankopon is caught speechless as a number of Marleyan airships descend from the sky.
Knowing that they will need more manpower to fight off Marley, Onyankopon begins releasing the soldiers who were imprisoned by the Yeagerists. He is immediately assaulted by Connie and Armin is forced to break the two apart. Onyankopon swears that he had no knowledge of the spiked wine or Yelena and Zeke's euthanasia plan. Jean points out that if they help Eren and Zeke they will be helping them bring about Zeke's euthanasia plan, but Onyankopon insists that they are vital to the defense of Paradis in check and can be kept under control until the Rumbling is activated. The soldiers agree to help in the battle and Onyankopon requests that they free the rest of the Yeagerists' captives.
After Eren activates the Founding Titan and begins the Rumbling, Zeke's Titans start attacking soldiers indiscriminately and swarming the military's headquarters. Onyankopon and the volunteers are saved by the Survey Corps, who eliminate all the Titans. After the fighting Onyankopon learns from Jean about Eren's plan to destroy the whole world, despairing that his own country will also be destroyed.
Floch offers to allow the Volunteers to live in the Eldian Empire as honorary Eldians following the Rumbling, and Onyankopon refuses. In retaliation, Floch decides to have Onyankopon and Yelena publicly executed. As Floch is explaining to the amassed crowd why the two are being killed, Onyankopon reminds the Eldians that part of the reason he wanted to help them was to free his own country from Marley. He condemns them for perpetuating the same violence that Marley did, but is interrupted when Jean fires four gunshots at him. All four shots miss and the Cart Titan suddenly appears, grabbing Jean, Onyankopon and Yelena in its mouth before departing.
The three are brought to Hange, Levi and Magath, where Jean reveals to Onyankopon that he has joined forces with Marley to stop Eren.
The next day, the group travels to Paradis' harbor to take the Azumabito clan's airship and pursue Eren with it, but find that Yeagerists are already occupying the harbor. When Annie suggests launching an all-out attack on the Yeagerists, Onyankopon explains that they cannot do anything that will endanger the Azumabito, as he will need their mechanics' knowledge to properly operate their plane. Magath interrupts the discussion, breaking Yelena's arm in an attempt to get her to cooperate, and Onyankopon creates a makeshift sling for her.
While their allies engage the Yeagerists, Onyankopon and other noncombatants are transported to the boat by Pieck. Once at the boat, Onyankopon works with the Azumabito mechanics to get the boat ready to sail to Odiha. After prepping the ship, Onyankopon calls upon his allies to evacuate. As his allies board, Onyankopon is shocked to see a Marleyan cruiser present at the port. Magath then hands Onyankopon an unconscious Falco Grice before informing him that he will stay behind to cover the rear.
- Yelena - One of the other high ranking members of the Volunteers, Onyankopon is on fairly good terms with Yelena. He has noted, though, that she is capable of incredible changes in character, with many of her actions causing him to become disturbed by how far she is willing to go to achieve her goals.
- Hange Zoë - Onyankopon has been on good terms with Hange since his arrival on Paradis. The two have worked together to considerably increase Paradis' technological advancements and, despite not appreciating them being held under house arrest, Onyankopon shares a mutual respect with Hange.
- Armin Arlert - Onyankopon noticed Armin was like him and sought out a peaceful solution to save Paradis instead of a militaristic one like many of the Eldians on the island and his fellow Volunteers. His mentioning of a God that wanted different races to exist in order for life to be interesting struck a chord with Armin and would ultimately save his life after the revelation of Yelena and Zeke's euthanasia plan is made known to the Survey Corps.
- Connie Springer - Although initially they had a stable relationship as both sides were helping Paradis' technological advancements, however, after the Anti-Marleyan Volunteers restrain the Survey Corps and members of the Blouse family, Connie begins to hate him, even attacking him after he opens the cell to free them, however, he begins to trust him after he says that he had no idea about the euthanasia plan.
- Jean Kirstein - Onyankopon had initially gained Jean's trust as their goals aligned, to develop Paradis Island's technology. However, after he, along with the rest of the Anti-Marleyan volunteers, restrain the Survey Corps, Jean begins losing trust in him. Despite this, Onyankopon frees him and the rest of the group and explains that he truly had no idea about the euthanasia plan, after his explanation, Jean trusts him again and chooses to help him.
- Sasha Blouse - Sasha was initially fascinated and confused about Onyankopon, mainly due to his skin color. However, after his explanation and both of them having the common objective to develop Paradis Island's technology, the two were on friendly terms.
- Nyankopon (alternatively spelled Onyankopon) is one of the names of the Creator God in the Akan religion.