Forbidden Arms: Bloodlust tells the story of a mysterious woman named Mayumi.
She possesses a powerful relic sword that seem to have a special affinity with blood, including hers. To counter the vampiric curse of the sword, she sleeps every 50 years.
She woke up, and overslept to 800 years later, the Earth is no more.
A catastrophic event took place and the world is now overrun by monsters and demons.