The Mysterious Class (Korean: 남고괴담; RR: Namgogoedam; lit. "Ghost Story in a Boys' School") is a 2021 South Korean web series featuring an ensemble cast consisting of the members of boy band Treasure—Choi Hyun-suk, Park Ji-hoon, Yoshinori Kanemoto, Kim Jun-kyu, Yoon Jae-hyuk, Asahi Hamada, Kim Do-young, Haruto Watanabe, Park Jeong-woo and So Jung-hwan—and their former co-members Mashiho Takata and Bang Ye-dam. Its plot centers on a group of 12th grade students in a boys' school who try to solve the mystery of their class' resident ghost.