Headhunted to Another World: From Salaryman to Big Four! Vol. 3 by Benigashira

IT'S CRUNCH TIME!The mighty Demon Army is facing a ferocious wyvern attack! But the true threat comes from deep divisions that are splintering the army. It's up to Uchimura, a human recruited into the Demon Army's Big Four, to use his office skills to heal the divisions and unite the Demon Army against this calamity.
Binding: Paperback / softback