A long time ago, the continent was peaceful until a black mist enveloped the kingdom, making ill all those who touched it. The citizens believed that it was the work of a demon lord and became scared to leave their own homes. When the beautiful princess also fell ill, the king beseeched someone to defeat the demon lord in exchange for a reward. One young man offered to do it in exchange for the princess’ hand in marriage. Together with his friends, he defeated the demon lord, who vowed to be resurrected one day to get his revenge. The young man returned to the cheers of the people who called him the ‘hero’. Claire greatly admires the hero who saved the world and thus, started on the path of the adventurer. However, there is not much work available for novices like her, so she does part-time at Len’s magic item shop. One day, she came upon an old magic sword in the shop. When she picked it up out of curiosity and swung it around, a dark glow emanated from it and a demon beast came out! While she was able to stave it off, the beast escaped from the shop. Not only that, but the sword had cast a curse upon her. With the help of the former adventurer Len, Claire embarks on a life-risking journey to drive back the darkness and rid the sword’s curse.