Moto Shinryuu, Chippoke na Ningen ni Tensei Shita kedo Musou Shimasu

The young boy Asval harbors a secret—his past life 300 years ago was that of the "Divine Dragon Bahamut," who protected the kingdom. He enjoys peaceful and happy days with his sister, though he feels frustrated by the weakness of being a mere human. However, while mining ore to buy medicine for his sister, he finds himself in an unexpected predicament, and suddenly, dragon wings sprout from his back—!? Furthermore, he is discovered by the army searching for the reincarnated Divine Dragon... A fantasy adventure in which he uses the power of a dragon to protect his family!

(Source: Overlap, translated)