|The Jaw Titan is an assault unit. Its small size makes it the swiftest of all. Its powerful claws and jaws can crush just about anything.|
|— A 瑪雷an analysis of Marcel's Jaw Titan|
那些擁有顎巨人力量的人以巨人的形式表現出可觀的速度和敏捷性，他們甚至可以移動得足夠快，以趕上九個巨人之一。 儘管顎巨人相對較小且較弱，但其移動性在 “巨人森林” 等地形中表現出色。
與所有九大巨人一樣，顎之巨人在尤米爾·弗利茲死後被帶入了世界。在她去世後的1,700年中，下頜巨人被關押在始祖巨人下屬的一個或幾個交戰的 艾爾迪亞恩房屋中。After these seventeen centuries when Karl Fritz, the 145th King of the Fritz family, abandoned the conflicts of Eldia and relocated to 帕拉迪島, the Jaw Titan was taken by the nation of 瑪雷 during the 巨人之戰.
Around the year 843, Marcel Galliard was chosen to inherit the power of the Jaw Titan. He would later make use of his Titan form during a war between Marley and an enemy nation, using his Jaw Titan to destroy the enemy's artillery guns.
In the year 845, the nation of Marley sent out Marcel, 萊納·布朗, 貝爾托特·胡佛, and 亞妮·雷恩哈特 across the ocean to Paradis Island as the start of the Paradis Island Operation. However, at some point before the attack on Shiganshina District, a Titan approached Reiner and nearly had him in its grasp until Marcel moved him away to safety. Marcel was caught in Reiner's place, and he was eaten alive as his comrades escaped. The Titan inherited Marcel's Jaw power and regained its human form: an Eldian girl named 尤米爾, who had been wandering as a Titan for around sixty years.
Choosing to start a new life for herself, Ymir made her way into humanity's territory and began living as a thief in the interior territories of the 城牆. At this time, she overheard the story of "Krista Lenz" from members of the Church of the Walls and her plans to join the 104th Training Corps. Desiring to meet her for political and personal reasons, Ymir joined the Training Corps in the same year as Krista.
At some point during their training, Ymir and Krista faced difficulties escorting a sick trainee to shelter in harsh winter conditions. Wanting to see Krista survive, she sent her off to the shelter alone and used the Jaw Titan to bring their fellow trainee to safety at the base of a cliff side. Krista wondered at how Ymir could have possibly reached the shelter before her. Ymir agreed to tell her secret to Krista under the condition that when the secret of her Titan power was publicly known, Krista would go back to living under her true name.
During the Wall Rose invasion in the year 850, 尤米爾 is among the recruits of the 調查軍團 when they are cornered by 巨人s at Utgard Castle. Seeing no hope for escape, Ymir chooses to make use of her Titan form to confront the Titans. Transforming before her friends' eyes, she battles the Titans at the base of the castle as the others comprehend the revelation of her powers. Reiner and Bertolt recognize her Titan as the one that ate Marcel five years ago and determine that they must capture her along with Eren when the time comes. When Ymir begins to struggle, Krista offers her encouragement. Ymir's Jaw Titan ascends the castle and saves the others from its collapse. When the dust settles, Ymir's fatigued Titan is unable to continue fighting against the Titans, but her life is saved by the arrival of the Survey Corps soldiers from the Stohess District raid. She is safely extracted from her Titan, and Krista reveals her true name as Historia Reiss.
Shortly afterward, when Bertolt and Reiner reveal their identities as the Colossus and 盔甲巨人s, Ymir is taken by the two Warriors along with Eren. After some questioning, Ymir agrees to cooperate with them in order to capture Historia. When the Survey Corps finds their location, she takes Historia into her Titan's mouth and escapes with Bertolt and the Armored Titan. Ymir remains within her Titan form throughout the escape, taking a moment early on to partially expose her human form in the nape in order to speak with Historia. Ymir abandons the Armored Titan when it is swarmed by a horde of Titans lured by Commander 艾爾文·史密斯 and assists the Survey Corps for a short time, but upon seeing Eren's use of the 始祖巨人 during the battle Ymir chooses to go with Reiner and Bertolt rather than staying with the Eldians of the Walls. After the battle, Ymir escapes with Bertolt and the Armored Titan to the ruins of Shiganshina District.
Marley arc[编辑 | 编辑源代码]
At the climax of the Marley Mid-East War during the battle of Fort Slava, Galliard is present in the trenches dug by the Marley 戰士隊 surrounding the fort. Cadet 柯特‧葛萊斯 suggests making use of Galliard's Jaw Titan and 皮克's 車力巨人 against the defenses of the Mid-East Allied Forces, but Commander Magath rejects the proposal due to the presence of anti-Titan artillery patrolling the perimeter of the fortress. However, once cadet 賈碧‧布朗 destroys the armored train carrying the artillery using explosives, Galliard is sent out onto the battlefield. His Titan proves to be more than enough to defend against the turret-fire from the bunkers surrounding Fort Slava, and Galliard's Titan makes quick work of Marley's enemies.
Galliard's attack on the Mid-East defenses is met with support from the 800-Warrior Unit and Pieck's Cart Titan in full battle armor. Using the immense strength of his Titan's jaws, Galliard rips the railways from the ground, ensuring a complete immobilization of the Allies' defenses. Shortly afterward, Galliard retreats as 吉克·葉卡 begins a Titan airstrike directly above the fortress, dropping dozens of Pure Titans onto the Allies. When Reiner Braun joins the fight as the 盔甲巨人, Galliard assists him in destroying the remaining anti-Titan artillery stationed within the ruined fortress.
Over a month later, the Jaw Titan returns during the Battle of Liberio when the 進擊的巨人 makes a sudden appearance and begins a massacre. The Jaw Titan swings onto the Attack Titan's back, attempting to bite into the nape to take the 始祖巨人, but its jaw muscles are sliced by 里維·阿卡曼 before the nape could be bitten through. The Attack Titan throws Jaws into the nearby building, where the 調查軍團 surrounds it in preparation for battle. The Cart and 野獸巨人s soon join the Jaw Titan in the plaza, and the Warriors prepare to battle the 艾爾迪亞ns of 帕拉迪島.
Observing the movements of the enemy's maneuvering equipment, the Jaw Titan leaps up from a building as an enemy soldier appears flying above the Cart Titan ready to launch a Thunder Spear, and slaughters the soldier mid-air. After the Attack Titan transforms once more, the Jaw Titan charges it, but is intercepted by 米卡莎·阿卡曼, who the Jaw Titan then engages.
It retreats after a quick flurry of strikes back to the husk of the War Hammer Titan.
The Jaw Titan spots an incoming airship that serves as the method of escape for the Survey Corps. It then goes to bring it down but is caught off balance due to Mikasa slashing its legs and severing one of its feet.
Crashing next to the Attack Titan, the Jaw Titan is further rendered helpless by getting both of its arms torn off by it. Then the crystal is jammed into its mouth and the Jaw Titan is unable to stop the Attack Titan from applying enough pressure to shatter the crystal, killing the holder of the War Hammer Titan. It is then knocked unconscious and about to be eaten by the Attack Titan, but is saved by the arrival of Reiner and his partially formed Armored Titan.