Set in an alternate reality where modern-day South Korea is governed by a constitutional monarchy descended from the Joseon dynasty, Siren Phillips learns that she will turn into a mermaid when she turns 12 years old. To make matters worse, she discovers that her friend's father is part of a group of hunters trying to catch her in which they attracted attention to the military and governments of both South Korea and North Korea under the leadership of King Lee Jae-ha and Queen Kim Hang-ah, his wife who also happens to be an officer with the North Korean Special Forces and the daughter of a high ranking Korean People's Army (KPA) official.
