She Professed Herself Pupil of the Wise Man (Manga) Vol. 1

Sakamori Kagami has woken up in the world of Ark Earth Online, a game he plays religiously. The catch? Instead of his normal avatar–an old, bearded sorcerer–he finds himself in the body of a girl! Now he must convince the people of this world that he–she–is a pupil of the legendary wise man who vanished without a trace thirty years ago.