Dear Sister, I've Become a Blessed Maiden Vol. 1

What seems like an ordinary spring break evening for Umehiko and his little sister, Momo, quickly turns to confusion when a mysterious symbol appears in the sky. Next thing the siblings know, they're in a strange world that's definitely not their own. But Umehiko is only concerned with making sure his sister gets back home safely. Unfortunately, right as he sends her back into the magical seal, he's pulled back and stranded in a whole new world! Theodorus, a powerful sorcerer who's been wor...