Bas-tee-ow Ven-toh-zo takes place in 1914 during the Vegan Campaign, where Antares launches a coastal invasion against Vega after struggling to break through stronger inland defenses of Murus Plateau. Instead of continuing a direct land assault, Antares shifts strategy and attacks a weaker point along the coast. The goal is to open a new front and push inland toward a key defensive position, an old Grusan castle known as Bas-tee-ow Ven-toh-zo, which means Windy Bastion.