One day, streamer Bai Xinxin is transmigrated into the prince's daughter, Bai Yueguang of the suspense game "Nightingale and the Rose". But everyone in this game is hell-bent on killing Bai Yueguang, and Lan Sha—who is controlled by the player—is the only one who can protect her.

Whilst fighting for her life against enemies known and unknown, in her struggle to survive from the jealousy of a bunch of yanderes, from the killing intent emanating from political opponents who object to the marriage alliance... Bai Yueguang tries to find a way to survive with Lan Sha by her side, too.

However, the main character "Lan Sha" doesn't seem to be a mere NPC...