After the sudden death of her twin sister, Hanin discovers a diary containing Hana’s final dream and secrets about her life at Sirius High School. To fulfill that dream, Hanin goes undercover as Hana and enrolls at Sirius High School. Unfortunately, while in disguise, Hanin finds herself caught up in the absurd life of the 12th-grade Science Class 4 and entangled in a love triangle with Joan and Jarvis, two handsome guys who each hold their own charm and mystery.