Sinma Hwansaeng

Feared as the Divine Demon, Cheon Jeong lived and died on the battlefield, knowing nothing but violence. When death finally claims him, it should have been the end. Instead, he awakens thirty years later in the body of Mujin Hwa, the powerless heir of a ruined clan. His overwhelming strength is gone, replaced by a frail body and enemies closing in from every side. To protect the siblings now in his care and reclaim a clan on the brink of collapse, the fallen legend must begin again and build a future from nothing.

(Source: WEBTOON)