Mao Nishiura 
Pens Down, Swords Up: Throw Your Studies to the Wind Volume 1 [EPUB ebook] 

The third son of a viscount, Allen Rovene has hated studying since the day he was born. And no wonder-after suddenly regaining the memories of his past life at the age of twelve, he realizes he spent the entirety of his previous life hunched over a desk, studying like a studyholic! Reborn into his dream world of swords and magic, he’s determined to make the most of his second chance by ditching the books and living a carefree, unburdened life-until he realizes the path to freedom has a detour in the form of the most renowned school in the kingdom: the Royal Knight and Mage Academy of Yugria. To become the magic-wielding, sword-swinging adventurer of his dreams, Allen’s going to have to repurpose his well-honed study skills toward one goal-passing the hellish entrance exams and heading to the Royal Academy!