The Legend of Heroes: Trails to Azure

Trails to Azure is set a few months after the ending of Trails from Zero. The protagonists: Lloyd, Elie, Tio and Randy, the police's Special Support Section (SSS), and their adoptive daughter KeA, are joined by new recruits – the Army sergeant major Noel Seeker and the former gang leader Wazy Hemisphere.
Upon reuniting, the SSS investigates the Red Constellation, an infamous mercenary corps which has set up a base in Crossbell. Randy reveals that the head of the Red Constellation, Sigmund, is his uncle, who wants Randy to follow in his father's footsteps as the corps' leader. The SSS is asked to provide security at a trade conference between the nations of western Zemuria. The conference is disrupted by terrorists targeting the leaders of Erebonia and Calvard, who escape from the building only to be killed by the Red Constellation and members of a Calvardian crime syndicate. The two nations use the incident to push for sanctions on Crossbell, but Crossbell's mayor, Dieter Crois, says it proves that Crossbell needs to be more autonomous. He begins planning a referendum for Crossbellan independence.
The SSS are sent to investigate the appearance of the secret society Ouroboros in the city, but members of the society defeat them and disappear. They also clash with the Red Constellation, who launches an attack on the city. Eventually, the referendum takes place. When pro-independence voters win, Crois declares Crossbell an independent state with himself as president, triggering hostility from Erebonia and Calvard. Later that day, the SSS discovers that the government has kidnapped KeA. While confronting the government's forces, they learn that KeA is an artificial human created centuries prior to embody the Sept-Terrion of Mirage, a powerful artifact gifted to humanity by the Goddess in ancient times which could control causality. It is also revealed that Crois, a descendant of the ancient alchemists that created KeA, is at the head of a conspiracy to use her power to make Crossbell a global superpower, along with his daughter Mariabell, Ouroboros, and the Red Constellation, whose attack was orchestrated by Crois to help win the referendum. KeA awakens her abilities and uses them to power weapons that annihilate the invading Erebonian and Calvardian forces, while the SSS is arrested and imprisoned.
A month later, Lloyd breaks out of prison and reunites the SSS, planning to rescue KeA. They infiltrate the city and defeat President Crois, only for his allies to abandon him. Mariabell uses magic and KeA's power to grow a massive Azure Tree on the outskirts of the city, initiating the final stage of the conspiracy's plan. The SSS use an airship to ascend the Tree and fight their way inward. Along the way, Randy defeats Sigmund and denies his destiny as a mercenary. At the top, Mariabell explains that even before her awakening, KeA could alter reality, and reveals that the SSS was originally killed by Joachim Guenter at the end of Trails from Zero before KeA intervened. She also states that KeA warped their emotions to make them love her. Agitated, KeA loses control and transforms into a monstrous avatar of the Sept-Terrion, which the party defeats. Afterward, KeA attempts to erase herself from existence, but Lloyd explains that their love for her was real, which convinces her to erase her power and remain with her family.
In the aftermath, the Azure Tree collapses and Crois' conspirators are arrested, except for Mariabell and Sigmund's daughter Shirley, who are recruited to Ouroboros. However, Crossbell is annexed by the Erebonian Empire, which leads into the events of the Trails of Cold Steel arc.