Tensei Daiseijo no Mezame: Shouki wo Joukashitsuzukeru Koto ni Juunen, Okitara Densetsu no Daiseijo ni Nattemashita

The Party of Heroes defeats the Demon King, a menace to the world. But as the enemy meets his demise, he unleashes miasma capable of destroying the entire world. In the face of despair, Saint Sophia makes the ultimate sacrifice to halt this devastating miasma. Years roll by, and when she finally awakens, she finds herself in a world twenty years into the future.

(Source: K Manga)