Powerful succubus has ambition to become a new queen of the kingdom so she infiltrates (all-female) group of royal knights and one by one starting with the commander of the knights she sneakily breaks them from the inside and transforms into demons.

Part 1 1-192
Part 2 193-358
Part 3 not yet released.

The series is on pixiv but image viewer on that website pisses me off so I decided to upload it here.
If you want to express your love to the author you can find this work here on pixiv:
https://www.pixiv.net/user/2783783/series/35889
Alternatively you can confess directly on twitter here:
https://twitter.com/sbtng_k