Remember 15
What is Remember 15 about (plot, summary)
"I miss you all.. Shall we reunite at the island?, a message from Lyla, a school queen who committed suicide 5 years ago, was sent to her friends, seniors, and sisters mysteriously. Despite the conundrum, everyone has somehow decided to return to that island again after reading the message. To their surprise as they reach on the island, the truce of darkness of the past reality unfolds. The beautiful dream island which everyone has ever dreamed of has turned out to be a bloodshed fight between those who called themselves as "friends".
If you don't remember, I will remind you.