Mahoutsukai no Yome: Hoshi Matsu Hito
I can't say for sure whether this Ova will play after the anime or in between. In any case, they do not contribute to the main plot.
However, these 3 Ova episodes surpass the anime in quality, both in terms of presentation, narration, and animation.
The story mostly tells events from Chise's past and one of her greatest experiences at the time, which wasn't that bad at all, I found this relatively interesting. The atmosphere was also right here.
In contrast to the anime series, it was again made clear how great the danger is of seeing the shadows of the magic world and how fatal it could be for people to have eye contact with them. Unfortunately, it has been neglected too much in the series, almost forgetting the topic.
To be honest, I find the Ova quite recommendable in contrast to the series, unfortunately, one lacks the context for it. So, unfortunately, you have to see the anime to understand everything.