In the late Edo-era kingdom of Kagetsu, a mysterious island suddenly appears far beyond the nation’s eastern waters.
The island is covered in blood-red trees, floating stone ruins, and strange creatures said to be neither human nor beast.
The first explorers sent by the shogunate returned as twisted living statues, frozen in poses of terror.

The island is renamed Akairo Rakuen — The Crimson Eden.

Seeking the secret to true immortality rumored to exist on the island, the shogunate creates a brutal decree:

“Send condemned criminals to retrieve the Crimson Elixir.”

Murderers, traitors, sorcerers, and forgotten warriors are given one final chance at freedom—
but only if they survive the island and return with the elixir.

To ensure obedience, each criminal is assigned a Yamibito Executioner, elite swordsmen trained to kill their assigned prisoner at the first sign of rebellion.
If the criminal attempts escape → the executioner beheads them.