The game is set in the Erebonian Empire and takes place after the
Trails in the Sky trilogy and concurrently with
Trails from Zero and
Trails to Azure. The plot is centered around "Class VII" at Thors Military Academy in Trista, a newly formed class at the academy and the only one not segregated by social class (composing of both Erebonian nobility and commoners). The class consists of protagonist Rean Schwarzer (a commoner later adopted into a noble family), Alisa Reinford (daughter of the chairman of an engineering company), Elliot Craig (the son of a famous commander from the Imperial Army), Laura S. Arseid (the daughter of a renowned warrior and noble), Machias Regnitz (the son of the Imperial governor), Jusis Albarea (the heir of one of the four Great Houses), Emma Millstein (a commoner accepted into Thors due to her exceptional grades), Fie Claussell (former member of a jaeger group called Zephyr), Gaius Worzel from the Nord Highlands, and class instructor Sara Valestein (a member of the Bracer Guild). They are later joined by Crow Armbrust (a second year who joins Class VII after failing to graduate), and Millium Orion (a member of Imperial Army's Intelligence Division). Throughout the school year, Class VII undergo
field studies that take them to various cities and areas across Erebonia. The primary purpose is for the class to witness first-hand the reality of the Empire, consumed in a power struggle between the aristocratic Nobles that command the Provincial Army, and the working class Reformists led by Chancellor Giliath Osborne, which threatens to lead to civil war. In the process, the students increasingly come into conflict with a terrorist group later known as the Imperial Liberation Front (secretly backed by the Noble Alliance), led by the masked charismatic leader known only as "C". They are also investigating their academy's old schoolhouse, which mysteriously grows and changes its layout every month. At the bottom of the old schoolhouse, after overcoming the final trial, they discover a mech known as a Divine Knight called "Valimar". During a speech by Osborne regarding Crossbell's recent bid for independence from Erebonia and the neighboring Republic of Calvard, he is assassinated by "C", revealed to be Crow. The assassination starts a civil war between the Noble Faction/Provincial Armies and Reformists/Imperial Army. Trista is invaded by the Provincial Army and Imperial Liberation Front. During the attack, Valimar offers to form a covenant with Rean, making him an "Awakener", one who can summon and pilot a Divine Knight, which Rean accepts. Rean uses Valimar to drive back the Provincial Army and Imperial Liberation Front, but Crow, revealed to also be an Awakener, arrives in Trista and challenges Rean with his Divine Knight, Ordine. After Rean is defeated, the rest of Class VII engages Crow, allowing Valimar to escape with Rean. ==Development and release==