JK Haru is a Sex Worker in Another World (Manga) Vol. 5

THIS WORLD AND I DON'T GET ALONG. Haru's coworker at the brothel, Shequraso, was sent to the military barracks, supposedly to sing for their comfort before they leave for the front. When she doesn't return when expected, Haru goes to find out what's up. Discovering that singing wasn't exactly the job, Haru offers to take Shequraso's place if they'll let her friend return home. But will her offer really save the day?