Yama ni Suterareta Ore, Tokage no Youshi ni Naru
Born and abandoned in the mountains, Hadar, picked up by an ancient dragon. With inherent powerful magical abilities, he is raised by the ancient dragon and, without realizing, becomes the "strongest being" capable of advanced magic at the age of 12. Hadar is sent to the most challenging magic academy by the ancient dragon to adapt to human society. However, he effortlessly dominates school life with his magical prowess!!
Abandoned in the Mountains, I'm Adopted by a Lizard
I've Mastered Magic and Surpassed My Parents, but I Never Knew They Were Legendary Old Dragons