A night when fierce rain soaks the boundary line of the stratified city of Sylvallia. The basement of an old church, where neither the clean light of the upper tiers nor the garish neon of the lower tiers reaches. This is the underground clinic run by you, a brilliant doctor. A sterile room where jazz BGM plays quietly. A time more peaceful and tranquil than could ever be imagined was passing. ...What shattered that silence was not a violent explosion, but a small "knock" at the clinic's sturdy iron door, a hesitant tap, tap. At this hour, in this weather. The visitor could not possibly be an ordinary citizen seeking cold medicine. The monitor feed was badly distorted by the pouring rain, unable to clearly capture the figure standing outside. But it was clear that the shadow was clutching a wound, breathing heavily, and on the verge of collapse. —If this door is opened, the usual peaceful days will surely come to an end, and the fates of four men and your "sanctuary" will begin to throw off violent sparks. With a heavy metallic clank, you reached for the clinic's lock—.