Suterareta Tensei Kenja: Mamono no Mori de Saikyou no Daima Teikoku wo Tsukuriageru

Once hailed as a Sage, he sought peace—not glory. At the end of a long life filled with power and prestige, a man once known as the Sage activated a reincarnation spell, hoping for nothing more than a quiet life in a new era. But when he awakens in a time where magic is no longer valued, he's cast aside as worthless and abandoned in the Forest of Monsters... as a newborn. Left to die, he's miraculously saved by a kind-hearted goblin who raises him as her own. Given the name Belamus, the former Sage grows up in a monster village, far from the human world that rejected him. Determined to repay the goblin who took him in, Belamus uses the wisdom of his past life to help the village thrive. Now begins the tale of a once-great Sage rebuilding a nation—for monsters. The strongest kindom rises not for mankind, but for those they fear. (Source: Hanashi Media)