Tensei Shitara Hime Datta node Dansou Joshi Kiwamete Saikyou Mahou Tsukai Mezasuwa.

Isabella is a protected princess in a magical world who is reincarnated as Ikuto, a regular high school boy? Ikuto is pleased to have the ability to use magic, but his hopes are dashed when he learns that women are not permitted to utilize magic in this world. Ikuto, however, is unwilling to give up and, at the age of sixteen, makes the decision to leave the castle and set off on a quest to become a magician. A brand-new phenomenon involving a handsome wizard with unique circumstances and a princess dressed as a guy, but secretly a high school kid!