Captain Kanone Amalthea is an officer serving in the Intelligence Division of the Royal Army.
Born in Grancel, 27 years before the start of the game, Amalthea joined the military academy, attending the same year as Julia Schwarz with whom she developed an academy rivalry, and graduating with excellent grades although her rival remained her better in combat skills. After graduation, she joined the military operations office where she met Colonel Richard and a year before the events of Trails in the Sky, she was reassigned to the newly-formed Intelligence Division to serve as Richard's second-in-command.
Estelle and Joshua first meet Captain Amalthea at the same time they meet Colonel Richard, though Amalthea's name isn't mentioned until she and Richard make a reappearance during the army's assault on the sky bandit lair. Both times, the captain remains in the background and doesn't contribute to the conversation taking place.
Amalthea shows a softer side to herself when she visits the campus festival at Jenis Royal Academy, where she's seen relaxing in the cafeteria, buying candy at one of the stalls, attending the school play and clearly having a good time. She briefly reappears together with the colonel after the arrest of Mayor Dalmore by the Royal Guard. Though Colonel Richard praises Lieutenant Schwarz for her quick response, Amalthea can't resist questioning her old academy rival on how she and her men could have learned about and responded to the situation so quickly. While Amalthea's question takes Schwarz off guard, Colonel Richard dismisses the matter and changes the subject.
Amalthea starts playing a more active role when she visits Central Factory Chief Murdock as representative of Colonel Richard after the attack on the factory and the abduction of Professor Russell. Stating that the attack was a clear-cut case of terrorism and mentioning that the army has sealed off the Zeiss region in order to prevent the culprits from escaping, she asks Dorothy to give up her photo quartz in order to process the picture of the escaping attackers as evidence, which Dorothy reluctantly does.
Amalthea's role in the conspiracy surrounding the kidnapping is revealed when Estelle, Joshua, Agate and Tita sneak into Leiston Fortress and eavesdrop on Colonel Richard and Amalthea interrogating the professor. While Amalthea leaves most of the talking to her superior, she draws the professor's ire by threatening that some "peril" might befall Tita if he doesn't start cooperating. After a report from 2nd Lieutenant Lorence that the Royal Guardsmen have been arrested, Amalthea, Richard and the Lieutenant board the Intelligence Division's airship and head for Grancel. After the infiltration into the fortress and Russell's disappearance are discovered, the colonel sends his second-in-command to Zeiss in order to see if the factory was in any way involved in the security breach at the fortress and her arrival forces Estelle and Joshua, who were waiting for their airliner to Grancel to arrive, to travel to the royal city on foot. The Central Factory management was expecting the army to investigate them and made sure to cover their tracks.
While speaking to Murdock and questioning him on his involvement, the captain also extends him an invitation to a royal banquet taking place after the conclusion of the Martial Arts Competition. During the tournament, Elnan mentions to Estelle and Joshua that Amalthea has been travelling the country and visiting all major cities and that the Bracer Guild is keeping an eye on her. While Estelle and Joshua assume her trip around the country is a veiled attempt at tracking down the professor, her real reason is visiting the remaining members of the Royal Assembly and pressure them into attending the banquet.
She returns to the royal city in time to attend the final match between the team headed by Zane and the team headed by Lorence. Annoyed by the latter's eventual loss, Amalthea scolds Lorence and accuses him of being all talk, but Richard cuts in and tells her that he asked Lorence to hold back. When she reminds her superior that Estelle and Joshua will be entering the castle tonight, Richard brushes it off and says that their plan is too far along for anyone to put a stop to it.
As the colonel's second-in-command, Amalthea is responsible for security in the castle and she's the one to formally welcome Estelle, Joshua and Zane to the castle. While polite on the surface, she makes an ominous inquiry into their activities in the Zeiss region and gives the accompanying maid a mildly threatening warning not to bore the guests with idle chatter before leaving. She's also present at the banquet and when Colonel Richard runs into Estelle and Joshua and invites them for a drink in the lounge. Sensing that the bracers could potentially be trouble, Amalthea hastily offers to prepare the drinks with the presumed intention to spike them, only for Richard, who sincerely wanted an opportunity to speak with Cassius' children, to dismiss her, much to her chagrin.
She maintains a vigilant eye on things throughout the evening and after receiving several reports of Estelle and Joshua entering and leaving the maids quarters, she questions the two bracers after catching them returning to their room. Before she can start pressuring them, however, an apparently drunk Zane walks in and starts hitting on her. Caught off guard and a bit intimidated by his height and mannerisms, she lets Estelle and Joshua off the hook and walks off.
When Richard takes off to explore the sealed area underneath the castle, he leaves matters on the surface in the hands of Captain Amalthea. When she receives word that the Erbe Royal Villa has been taken over by the bracers and the Royal Guard, she furiously commands her soldiers to strengthen the castle's defenses and summon reinforcements from other regions. The next day, Joshua and his team manage to infiltrate the castle and open the gate, allowing a battalion of bracers and royal guardsmen to enter the lobby. Amalthea, who's on the royal terrace at the time quickly sends all the remaining soldiers to the gate only to realize she got tricked when a confiscated airship touches down on the balcony and Estelle, Kloe and Scherazard jump out. The captain engages the three of them in battle with the assistance of two of her guards, but is defeated and knocked out.
After Estelle, Joshua and their companions enter the Sealed Area and breach its lower levels, they find Amalthea waiting for them once more. Instead of relying on guards, she calls two archaisms to her side this time and once again engages the party. Despite her claim that she can now easily control the ancient mechanisms, she struggles to keep the robots under control and is once again defeated. Her unconscious body remains at the party's second camp until the activation of the black orbment where, after the rest of Estelle's and Joshua's companions head to the bottom level to provide assistance, she manages to get away and is presumed to still be hiding in the ruins by the time the coup is thwarted and the Birthday Celebration takes place.
Amalthea returns in Trails in the Sky SC at which point she is in hiding, being one of the few Intelligence Division members who have evaded justice. She leads a small contingent of Special Ops soldiers and plots to free Colonel Richard from prison. Amalthea ends up becoming an unwitting pawn of the Ouroboros society who exploit her desire to free Richard in order to get her to participate in one of their "experiments." The plan involves using the Orguielle, an orbal tank the Intelligence division was developing in secret--now equipped with one of the new state-of-the-art engines and a Gospel capable of disabling all orbal devices in its vicinity while leaving the tank operational. She kidnaps Duke Dunan and with the Orguielle plans to storm Grancel Castle, oust Queen Alicia, and place the duke on the throne. The reasoning behind this is presumably that the duke (either of his own volition or as a figurehead acting under duress) will free Colonel Richard and pursue the militaristic governmental policies the colonel advocated.
Her plans are ultimately foiled by Julia Schwarz and the Royal Guard with help from the Bracers' Guild and Father Kevin Graham. After her defeat, she is dejected and realizes she being manipulated by Ouroboros. She initially refuses to cooperate with the Army and Bracers' joint investigation into the society, but then Richard is (temporarily) hauled out of prison to tell her to do so.
Her fervent loyalty to Colonel Richard even after his arrest shows how she idolizes him and is perhaps in love with him.
She's also a former academy rival of Julia Schwarz