>>4345
I understand how you feel, I also hate it when they finish the manga after the first volume, since the chances someone will pick the LN up are so low, these promotional series just create itches they don't plan on scratching.
That said, there is one adaptation which I consider excellent for Maoyuu. It's ongoing too, so no rushed ending, and they're probably planning on adapting the entire thing.
http://bato.to/comic/_/comics/maoyuu-maou-yuusha-be-mine-hero-i-refuse-r643