Death March to the Parallel World Rhapsody, Vol. 18 (Manga)

Rin finds herself stuck in a mock battle with Prince Sharorik, but despite her combat prowess, she already knows she's going to lose. Or more accurately, she has to lose. But suddenly, a timely interruption by a greater demon puts an end to the duel, forcing the two warriors to team up and take it down! However, this new opponent is a force to be reckoned with, and as the clash between the hero's party and a group of high-level demons unfolds, there's no guarantee they'll make it out unscathed...