Louis tests the player's blood and reveals that they are a 'Void-type', as their Blood Code has been damaged in some manner, allowing them to use the Blood Code of whoever shares their blood with them. Louis introduces the pair to his comrade Yakumo Shinonome as their group is seeking to remedy the Blood Bead scarcity. The player and Io meet Louis Amamiya, who sees the player successfully make contact with the vestige of a Lost without becoming frenzied, acquiring that Lost's memories and their Blood Code (a unique property to every Revenant that grants them their personal powers.) The player also demonstrates the ability to clear away the miasma, allowing for safer travel throughout Vein and exploration of the Bloodsprings. Guided by a girl in white named Io to a Bloodspring plant, the player learns that society is falling apart due to the scarcity of Blood Beads caused by a levy and distribution system and the strict protection of the very few humans remaining in the city, both enforced by Silva's provisional government, established shortly after Operation Queenslayer, leaving bloodthirsty Revenants to frenzy and turn into the Lost. The player awakens in the ruins of a city known only as Vein sealed within a red ring of mist, the land inside known as the Gaol of the Mists. Though they succeeded in killing Cruz, the Lost and the miasma remain, requiring Revenants to wear filtration masks to avoid turning Lost, and the Bloodsprings (plants that produce Blood Beads, which serve as an alternative to human blood) begin to dry up. More Revenants are created to defeat the Queen in a mission dubbed Operation Queenslayer, led by Cruz's father Gregorio Silva. Participating in an experiment to stabilize the Revenant population and stave off the Lost, a young girl named Cruz Silva volunteers to become the 'Queen of the Revenants', though she later frenzies herself and goes on a murderous rampage. Over time the number of Lost increases to the point where they begin to collectively emit a deadly Miasma, that hastens a Revenant’s blood-thirst and chances of frenzy.

Revenants can only die if their heart is destroyed, and require human blood as nourishment to keep themselves from entering a frenzy and mutating into the Lost - cannibalistic beings devoid of reason and control. In order to fight the monsters that began emerging around the world humanity created the Revenants: human corpses brought back to life by implanting a Biological Organ Regenerative (BOR) parasite within the heart, acting as vampiric fighters with unique abilities. Set in the near future, the world has fallen to a mysterious calamity known as the Great Collapse. ( October 2019) ( Learn how and when to remove this template message) Please help improve it by removing unnecessary details and making it more concise. This section's plot summary may be too long or excessively detailed.

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