I did some digging and this manga is only the first book (the second book manga is here: https://www.mangago.zone/read-manga/karasu_wa_aruji_wo_erabanai/)
Based on Amazon saying this is a 11+ hour audio book, I think we can go out on a limb and say this first volume is finished. They might not be counting it as complete in case the other books are not published under a different name as manga. But since the second book has a manga and this has gotten an anime, it's not impossible to think this series will continue. Let's keep an eye out for the others, shall we?
The series is Yatagarasu ( https://en.m.wikipedia.org/wiki/Yatagarasu_(novel_series) )
The author is enough to find the books.
is it finished?