@meowbe At page 9, there are two errors I can spot: "Where were", which should be "which were", and "an unique", which should "a unique". Because unique has the y sound, and not the u sound, it follows the grammar of consonants, not vowels.
Other than that, I don't find much issues with your sentences! But maybe use grammarly to find issues like the one I put above, since it is a bit hard to spot.
It seems Maou-sama really thirsts for Yuu so much. I never expected her to become depressed without his presence. She even has all sorts of merch based on him now! I mean, Bromides? Her servants are really going the extra mile to help her with Yuu's absence. Yuu, you'd better take responsibility now, or she'll fall into deeper degeneracy pretty soon! Just be there for her!