If you liked the Witch Craft Works manga, the Anime-Planet community thinks you'd like:
Both manga have somehwat similar female lead. In both cases it is a rich and non-emotional girl who declares that she will protect that average guy male lead. Though the guy in Shiki Tsukai is a bit above the average and despite what the girl promised to do, he actually has to fight himself. Nonetheless, if you liked one of those female leads you might find the other manga interesting too.
P.S. In both series the male lead is called a "princess" at some point...
There are some similarities between Witchcraft Works and Trinity Seven, like the protagonist suddenly finding himself surrounded by mages\witches, but truth to be told, I wanted to use the differences between those two series to encourige you to read Trinity Seven. Do you have enough of those wimpy, indecisive male leads? If the answer to that question is "yes", then Trinity Seven, might be just what you are looking for. The protagonist there openly states what's on his mind (witch often get him into trouble), and stays cool through (almost) any crisis. As a bonus it also has a high school setting, magic and mages.