Mahou Shoujo Site Sept

Mahou Shoujo Site Sept is a spin-off off the main Mahou Shoujo Site manga and it serves only as an "explanation" arc of the things that weren't shown in the main manga. But it doesn't really show anything either. You better not read this manga if you haven't read the main series and should read this after chapter 77 (Vol. 11 Ch. 77 - ENTER 22), as it has almost no connection to the main series before.

The story tellls us about Nagatsuki Hyouka and Takahashi Tsurara, who are, just like any of the Mahou Shoujo Site school girl characters, carry some kind of misfortune and receive a stick at the start of the manga. But the thing is that Hyouka did not receive the stick and took it from Tsurara, who actually was misfortunate enough to get it.
The third main character related to main manga is Isoko Anjou, and this spin-off tells almost NOTHING about her character, only telling her plans in the final chapter and leaving the rest for the main (ongoing) series, where she hardly ever appeared too.

It also contains mini extra story of a girl not affiliated with the main series, and it's pretty sad one.

Art style in this one is way worse than in the original.

Overall, it's great that this was released as a spin-off instead of showing this story as a flashback in the main manga to stretch it. It also made some stuff from horrible anime canon, but still left a lot of unanswered questions. As I said in the first paragraph - only read after chapter 77 to not fill your head with useless info.

Mahou Shoujo Site Sept serves as a spin-off of the Mahou Shoujo Site series. Therefore, reading it is not crucial to the main story.
The art was pretty average, not better or worse than in the series. What I did like were new magical weapons and abilities. Weak sides of this manga are mostly characters which lack development and quite predictable story. Some of the characters appear also in Mahou Shoujo Site, but that it not interfering with the story.
Overal for me 6/10 since I didn´t enjoy this story as much the other works from this author. However, the manga is quite short, so you should give it a try.