A maritime market in a certain perfecture on a solitary island not on any map.
The main character, Jun Hayami, headed for that island along with her colleagues.
Their objective was to go to a facility on the island where certain research was carried out, and find out the cause for the gunfire alarm that had activated there.
It was probably just an incorrect report...
Such expectations were quickly trampled, as they arrived on the spot of a veritable outbreak.
The virus under research at the facility had run rampant and possessed the bodies of the researchers and their associates, turning them into grotesque monsters!

[From dlsite]