School of Horns(2016)

Tsuno no Gakuen

In a world where horns are the defining trait of magic beings, larger horns mean more powerful magic! Eru, a freshman at a school for magic, is self-conscious about how tiny his horns are compared to those of his new classmates -- Not only is his magic so weak it is barely noticeable, but things have a habit of going awry when he is around. He is the complete opposite of Rihito, one of the top students of their grade with exceptionally strong magic...who is Eru's roommate!? And already seems to hate him!?
With their continued encounters, will Eru continue to discover just how inferior his strength is? Or maybe, he just might find some power of his own...

(Source: Yen Press)