Gate 7 manga

Gate 7 summary:

From Baka-Updates: An innocent sightseeing trip to Kyoto opens up a magical realm to shy high schooler Chikahito Takamoto. Visiting a legendary shrine, Chikahito finds himself in the mystical world of Hana and her comrades—and his immunity to their powers leads them to believe that he’s no ordinary awkward teenager! Protecting our world from violent elemental beasts, Hana and her team welcome the confused Chikahito—who isn’t quite sure that he wants to be caught in the middle of their war! One thing’s certain, though: since he’s smitten with aloof, childlike warrior Hana, he’s along for the ride, for better or worse!