Thread and Armor

Emery is a young girl traveling across an island ravaged by curses. A curse-breaker, she enters a dungeon and encounters a swordsman completely riddled with curses. He's been in the dungeon for hundreds of years, in a totally reckless attempt to take down a dragon, one of the mighty monsters known as the "Calamities" that were responsible for plunging the island into its cursed state. When Emery breaks his curses and his blade finally strikes the dragon, she discovers a shocking truth! A fantasy tale of mourning that follows a swordsman burdened by his past and a young curse-breaker.

(Source: Kodansha, translated)