A girl wakes up in a huge secret laboratory, then accidentally meets another girl who is trying to protect her house from a gang. The mystery girl overthrows the gang with her unexpected powers, and laboratory staff set out to find her.

Mi-so and Ha-eun meet in elementary school and quickly become best friends. In high school, Ha-eun meets Jin-woo and starts to have feelings for him, but he starts to have feelings for Mi-so. When they all meet again as adults, they are very different people, but they try to remember what friendship is really about.