Secrets|BTS Fanfic

Min Yoona and Kim Yoonbyul are identical twins, separated after one is adopted at the age of 5. Min Yoona lives at the Love House, an orphanage in Tongyeong, South Gyeongsang Province, where the younger kids look up to her as a mother figure. However, she hides the fact that she is bullied at school by a gang of mean girls led by Go Sang-Hee, while teachers turn a blind eye.
On the other hand, Kim Yoonbyul is studying at Sekang High School, the greatest private high school in Seoul's Gangnam District. Yoonbyul's best friends are Jo Ji-Hyun and Lee Su-Ji and she shares a mutual attraction with Jeon Jungkook, the school's singing star. They have been friends since they were 8 years old.
Min Yoona and Kim Yoonbyul look exactly alike, but only Yoonbyul is aware of the other's existence. Unlike the cheerful Yoona, Yoonbyul is prickly and secretive.
One day, on a school field trip to Tongyeong, Yoonbyul mysteriously disappears. At the same time,
Yoona is unjustly expelled from her school and jumps off a bridge in a suicide attempt......

This is really similar to the kdrama, Who Are You: School 2015. Some things would be changed but it is mostly the same.