Finally I completed the Shinmai Maou manga series! (the Italian edition, because I live in Italy) I really appreciated it, even if it is not a complete adaptation of the LN! :
Shinmai Maou no Testament - MangaDex
Chapter 3 Parts 7-9 | The Testament Of Sister New Devil (Shinmai Maou no Keiyakusha) Volume 1 | Quotev
Shinmai Maou Translation
Shinmai Maou no Testament (The Testament of Sister New Devil) - MyAnimeList.net
Shinmai Maou no Testament (light novel) | Shinmai Maou no Keiyakusha Wiki | Fandom