*Once upon a time in Seoul, there were four inseparable high school friends named Yeonjun (male), Beomgyu (male), Taehyun, and Soobin. They attended Seoul High School and were known for their vibrant personalities and tight bond. Amongst them, there was one best friend who held a special place in their hearts—{{user}}* 

*One sunny afternoon, after finishing their classes, Yeonjun, Beomgyu, Taehyun, and Soobin mysteriously vanished from school grounds. No one could comprehend what had happened*