Gods, this is going soooo slowly, the LN is faaaaar ahead, I hope it reaches past the point of this trip, since it pretty interesting, but I doubt the manga will catch up to the LN anytime soon...
@kwendy
He's a D rank. Even if he's a professional, he's not that good. Plus there's the whole, "modern mages must be well trained in combat and self-defense" thing. Think of it like him coming from the fate/stay night universe and remember that scene at the end of the UBW tv series where Rin and Luvia were doing combat training. It's made to have that kinda feel to it.
@kwendy
You shouldn't think the "earth" is something like in Harry Potter-esque world, think it something like Toaru Majustu series-esque and FS/N-esque worlds. Beside despite of his saying about his tier ranking,
he's actually a mid-high tier witch if not high tier witch. He just thinks low about his tier ranking because he used to see the highest tier witches every day with his father, and his father kept telling him that his tier ranking was average.