World's End Harem: Fantasia Vol. 13 (manga)

Under the orders of Princess Deila, Retta has come to Nargala to meet Arc, a man who may be connected to the Madilis Empire, according to Olga. After infiltrating Arc’s coronation, Retta ends up dispatching a suspicious attendee, and learns of Arc’s true relationship with the empire. An alliance is formed between Retta and Arc, and the stage is set to topple the empire! But are their combined powers enough to take on the empire’s enormous army? Meanwhile, Lati questions Olga’s motives in regards to their own shared goal. What does the demon woman have planned?