Armored Titan

"Nothing seems to work on him... not Eren's attacks, not my blades. And he's not like Annie. His whole body is constantly hard."

- Mikasa struggles against the Armored Titan's power

The Yoroi no Kyojin (鎧の巨人) is one of the Nine Titans that possesses armored plates of skin across its body. It is currently in the possession of Reiner Braun, though it will soon be passed on to a cadet from among the warriors.

Armored skin
The defining feature of the Armored Titan is the all-encompassing layer of plated, armor-like segments of hardened skin protecting the Titan body. This armor is capable of protecting the Titan form from significant amounts of damage, even a direct hit from a cannon or the ultrahard steel blades of vertical maneuvering equipment. However, the armor has some limitations and is not capable of protecting the user from high-power weaponry such as the Mid-East Allied Forces' anti-Titan artillery.

One disadvantage of the Armored Titan's skin is the decreased speed of the Titan form. Whether due to increased weight or restrained movement, the Armored Titan is incapable of moving at high speeds when completely armored. This can be alleviated if the user chooses to shed segments of the armor to increase movement capability, such as the armor behind the knees.

History
The Armored Titan, like all the Nine Titans, was brought into the world after the death of Ymir Fritz. In the 1,700 years following her death, the Armored Titan was held in the possession of one of the eight warring Eldian houses subservient to the Founding Titan. After these seventeen centuries when the 145th King of the Fritz family abandoned the conflicts of Eldia and relocated to Paradis, the Armored Titan was taken by the nation of Marley during the Great Titan War.

At some point before the year 845, Reiner Braun was chosen to inherit the power of the Armored Titan. Some time later, the nation of Marley sent out Reiner, Bertolt Hoover, Annie Leonhart, and Marcel across the ocean to the island of Paradis as the start of the plan to regain the Founder. After arriving on the island and venturing northwards to the Walls, Reiner entered into Shiganshina District, the southernmost territory of Eldia, after Bertolt destroyed the south gate with his Colossus Titan. As panicked Eldians fled the city while Titans swarmed in, Reiner's Armored Titan advanced to the north gate and charged it, breaking through and breaching the northern part of Wall Maria. Reiner joined his fellow surviving warriors in entering the walled territory during the chaos, and he would not use the Armored Titan for another five years.

Story
Five years after the fall of Wall Maria, the warriors of Marley learn of Eren Yeager's possession of the Attack Titan. Believing that he may be the current holder of the Founding Titan that they are searching for, Reiner does not use his Armored Titan to breach Wall Rose's northern gate after Bertolt Hoover breaches the southern gate of Trost District with his Colossus Titan. Instead, the warriors turn their full attention to Eren. Over a month later, Reiner reaches a breaking point and chooses to reveal his nature as the Armored Titan as well as Bertolt's nature as the Colossus Titan to Eren, promising to leave the people of the Walls alone if he returns with them to their hometown. When Eren refuses and Mikasa attacks the two warriors, Reiner transforms into the Armored Titan to capture Eren. However, Eren in turn transforms into the Attack Titan and battles with Reiner.

Despite improvements to his control over the Attack Titan, the Armored Titan overpowers him initially until Eren makes use of a lock that was taught to him by Annie Leonhart some time ago, taking one of the Armored Titan's arms before retreating temporarily. Requiring more speed, Reiner begins shedding the armor behind his knees and continues his attack on Eren, but he is nonetheless overpowered by the Attack Titan again. With defeat imminent, Reiner calls for Bertolt's Colossus Titan, which falls on the two Titans in an explosive burst of steam. The Armored Titan is able to withstand the intense winds and bites Eren out of the Attack Titan. Once Bertolt exits his Titan with a captive Ymir, the warriors escape to a nearby Titan Forest. After some conversation in the forest, the warriors start their retreat upon seeing signal flares from the Survey Corps approaching. Reiner uses his Armored Titan to carry Bertolt and their captives away, and the Survey Corps pursues them. The Armored Titan's retreat goes unhindered until Commander Erwin Smith charges the Titan head-on with a horde of mindless Titans following after him. The Armored Titan attempts to fight back against the Titans, and the warriors lose Eren to the Survey Corps in the moment of vulnerability. Shortly afterwards, Eren succeeds in temporarily using the Founding Titan, causing the Titans to swarm after the warriors. The Armored Titan flees with Bertolt and Ymir, and they rest in the ruins of Shiganshina District. Some time later, Reiner's Armored Titan battles Zeke Yeager's Beast Titan over their next course of action. The Armored Titan is defeated in the brawl, and Zeke states that they will wait in Shiganshina for the arrival of the Survey Corps rather than attempting to rescue Annie Leonhart, the Female Titan.

Three months after the battle of Trost District, the Survey Corps arrive in Shiganshina and seal the southern breach using a new hardening ability acquired by the Attack Titan. Suspecting that the warriors may be nearby, Armin Arlert proposes a search of the Wall and Reiner is found hiding within. As he is attacked by Captain Levi, Reiner uses one of his last-resort Titan powers to transfer his brain functions to the entirety of his body long enough for him to transform into the Armored Titan. As the battle of Shiganshina District begins, Reiner hardens his fingers to climb Wall Maria in order to attack the Survey Corps' horses. However, Eren's Attack Titan appears in the city and Reiner is left with a choice of attack. Reiner chooses to confront Eren, and the Attack Titan battles with the Armored Titan for a second time. Eren's new ability to harden the Attack Titan's skin successfully deals heavy damage to the Armored Titan, but the greatest damage is dealt from the Thunder Spears, a new explosive weapon developed by the Survey Corps in recent months. The explosives tear through the armor of Reiner's nape and destroy his brain, though his consciousness transfer once again keeps him alive. The Armored Titan calls for plan B, the Colossus Titan, and shortly thereafter Bertolt arrives at Reiner's side, telling him to lie down on his back for the time being. While Bertolt confronts the Survey Corps, Reiner follows Bertolt's advice and the Armored Titan lies down on its back, protecting Reiner from further harm and allowing for him to regenerate his body. A short while later, Reiner fully heals his brain and the Armored Titan returns to the fight, but with no memory of any events that had occurred since earlier that morning. The Survey Corps attacks Reiner with the Thunder Spears again, incapacitating it and successfully bursting Reiner from the nape of the Armored Titan. Reiner is interrogated afterwards, but before he can be killed he is rescued by Zeke and Pieck's Cartman, who brings him atop Wall Maria. The warriors would return to Marley afterwards, abandoning Annie and Bertolt.

Four years later, Reiner is present at the battle of Fort Slava at the climax of the Marley Mid-East War, waiting on standby in an airplane due to the presence of anti-Titan artillery on the ground below.